mirror of
https://github.com/erkyrath/infocom-zcode-terps.git
synced 2026-01-11 23:43:24 +00:00
979 lines
26 KiB
NASM
979 lines
26 KiB
NASM
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PAGE
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* ---------------------------------------------------------------------------
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* ZIP MAIN INSTRUCTION-FETCH CYCLE
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* ---------------------------------------------------------------------------
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* OPERATORS WHICH ACCEPT A VARIABLE NUMBER OF ARGUMENTS (OPQEQU, OPCALL, ETC)
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* ARE IDENTIFIED BY AN INITIAL NOP. THEIR ARGUMENTS ARE PASSED IN AN ARGUMENT
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* BLOCK, WITH THE NUMBER OF ARGUMENTS AS THE FIRST ENTRY. ALL OTHER OPERATORS
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* RECEIVE THEIR ARGUMENTS IN REGISTERS.
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NOOP EQU $4E71 * MARKS ROUTINES WHICH TAKE OPTIONAL ARGS
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NXTINS BSR NXTBYT * GET THE OPERATION BYTE
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IFEQ DEBUG
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BSR DBTEST
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ENDC
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CMPI.B #$80,D0 * IS IT A 2 OP?
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BCS.S NXT2 * BLO * YES
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CMPI.B #$B0,D0 * IS IT A 1 OP?
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BCS.S NXT1 * BLO * YES
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CMPI.B #$C0,D0 * IS IT A 0 OP?
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BCC NXT4 * BHS * NO, MUST BE AN EXTENDED OP
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* ---------------------------------------------------------------------------
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NXT0 ANDI.W #$0F,D0 * 0 OP, EXTRACT OPERATOR CODE, "xxxx oooo"
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ADD.W D0,D0 * WORD OFFSET
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LEA ZEROPS,A1
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ADDA.W 0(A1,D0.W),A1 * CALCULATE THE OPERATOR ROUTINE ADDRESS
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PEA NXTINS * LEAVE RETURN ADDRESS ON STACK
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JMP (A1) * CALL THE OPERATOR ROUTINE
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* ---------------------------------------------------------------------------
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NXT1 MOVE.W D0,D2 * 1 OP, MAKE A COPY, "xxmm oooo"
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ANDI.W #$0F,D2 * EXTRACT OPERATOR CODE
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ADD.W D2,D2 * WORD OFFSET
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LSR.W #4,D0 * EXTRACT MODE BITS
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ANDI.W #3,D0
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BSR GETARG * GET THE ARGUMENT
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LEA ONEOPS,A1
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ADDA.W 0(A1,D2.W),A1 * CALCULATE THE OPERATOR ROUTINE ADDRESS
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PEA NXTINS * LEAVE RETURN ADDRESS ON STACK
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JMP (A1) * CALL THE OPERATOR ROUTINE
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* ---------------------------------------------------------------------------
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NXT2 MOVE.W D0,D2 * 2 OP, MAKE A COPY, "xmmo oooo"
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MOVEQ #1,D0 * ASSUME FIRST ARG IS AN IMMEDIATE
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BTST #6,D2 * IS IT INSTEAD A VARIABLE?
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BEQ.S N2X1 * NO
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MOVEQ #2,D0 * YES, CHANGE MODE
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N2X1 BSR GETARG * GET THE FIRST ARG
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MOVE.W D0,D1
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MOVEQ #1,D0 * ASSUME SECOND ARG IS AN IMMEDIATE
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BTST #5,D2 * IS IT INSTEAD A VAR?
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BEQ.S N2X2 * NO
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MOVEQ #2,D0 * YES, CHANGE MODE
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N2X2 BSR GETARG * GET THE SECOND ARG
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EXG D0,D1 * POSITION THE ARGS
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ANDI.W #$1F,D2 * EXTRACT OPERATOR CODE
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ADD.W D2,D2 * WORD OFFSET
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LEA TWOOPS,A1
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ADDA.W 0(A1,D2.W),A1 * CALCULATE THE OPERATOR ROUTINE ADDRESS
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CMPI.W #NOOP,(A1) * BUT DOES THE OPERATOR EXPECT AN ARGBLK?
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BNE.S N2X3 * NO
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LEA ARGBLK+6(A6),A0 * YES, MOVE ARGS TO ARGBLK
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MOVE.W D1,-(A0)
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MOVE.W D0,-(A0)
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MOVE.W #2,-(A0) * ALWAYS 2 ARGS
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N2X3 PEA NXTINS * LEAVE RETURN ADDRESS ON STACK
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JMP (A1) * CALL THE OPERATOR ROUTINE
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* ---------------------------------------------------------------------------
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NXT4 MOVE.W D0,D2 * EXTENDED OP, SAVE A COPY, "xxoo oooo"
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*** GET THE 4 (OR 8) MODE SPECIFIERS, EXTRACT AND STACK THEM ...
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IFEQ EZIP
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CMPI.B #$EC,D0 * IS THIS AN XCALL (236)?
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BNE.S N4X1 * NO
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MOVEQ #8,D3 * YES, 8 MODE SPECIFIERS
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BSR NXTBYT * GET THE FIRST MODE BYTE, "aabb ccdd"
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MOVE.W D0,D1
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BSR NXTBYT * GET THE SECOND MODE BYTE, "eeff gghh"
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MOVE.W D0,-(SP) * SAVE hh
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LSR.W #2,D0
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MOVE.W D0,-(SP) * SAVE gg
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LSR.W #2,D0
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MOVE.W D0,-(SP) * SAVE ff
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LSR.W #2,D0
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MOVE.W D0,-(SP) * SAVE ee
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MOVE.W D1,D0
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BRA.S N4X2
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ENDC
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N4X1 MOVEQ #4,D3 * 4 MODE SPECIFIERS
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BSR NXTBYT * GET THE MODE BYTE, "aabb ccdd"
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N4X2 MOVE.W D0,-(SP) * SAVE dd
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LSR.W #2,D0
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MOVE.W D0,-(SP) * SAVE cc
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LSR.W #2,D0
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MOVE.W D0,-(SP) * SAVE bb
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LSR.W #2,D0
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MOVE.W D0,-(SP) * SAVE aa
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*** DECODE ARGUMENTS, STORE IN ARGBLK
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CLR.W D4 * KEEP A COUNT OF ACTUAL ARGUMENTS
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LEA ARGBLK+2(A6),A1 * ARGUMENT BLOCK, SKIP OVER COUNT SLOT
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N4X3 MOVE.W (SP)+,D0 * POP NEXT MODE SPECIFIER
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ANDI.W #3,D0 * EXTRACT MODE BITS
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CMPI.W #3,D0 * ARE THERE ANY MORE ARGUMENTS?
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BEQ.S N4X4 * NO
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ADDQ.W #1,D4 * YES, COUNT THIS ONE
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BSR GETARG * DECODE AND FETCH IT
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MOVE.W D0,(A1)+ * STORE IT IN ARGUMENT BLOCK
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SUBQ.W #1,D3 * GO FOR MORE
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BNE.S N4X3
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BRA.S N4X5
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N4X4 SUBQ.W #1,D3 * NUMBER OF EXTRA MODE SPECIFIERS
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ADD.W D3,D3
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ADDA.W D3,SP * FLUSH THEM
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N4X5 LEA ARGBLK(A6),A0 * PASS ARGBLK POINTER TO THE OPERATOR HERE ...
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MOVE.W D4,(A0) * STORE NUMBER OF ARGUMENTS
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*** CALCULATE THE OPERATOR ROUTINE ADDRESS
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ANDI.W #$3F,D2 * EXTRACT OPERATOR CODE
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ADD.W D2,D2 * WORD OFFSET
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LEA EXTOPS,A1
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ADDA.W 0(A1,D2.W),A1 * CALCULATE THE OPERATOR ROUTINE ADDRESS
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CMPI.W #NOOP,(A1) * BUT DOES THE OPERATOR EXPECT AN ARGBLK?
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BEQ.S N4X6 * YES
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ADDQ.L #2,A0 * NO, PASS ARGS IN REGISTERS
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MOVE.W (A0)+,D0
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MOVE.W (A0)+,D1
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MOVE.W (A0)+,D2
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MOVE.W (A0)+,D3 * MAXIMUM OF FOUR
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N4X6 PEA NXTINS * LEAVE RETURN ADDRESS ON STACK
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JMP (A1) * CALL THE OPERATOR ROUTINE
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PAGE
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* ---------------------------------------------------------------------------
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* DISPATCH TABLES
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* ---------------------------------------------------------------------------
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* UNIMPLEMENTED OPCODES DISPATCH TO HERE ...
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OPERR CLR.W D0 * (MAY BE GARBAGE)
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LEA MSGBAD,A0
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BRA FATAL * 'Bad operation'
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SECTION ZDATA
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MSGBAD DC.B 'Bad operation',0
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SECTION ZCODE
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* FOLLOWING MUST BE IN CODE SECTION, DUE TO OFFSET COMPUTATIONS ...
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ZEROPS DC.W OPRTRU-ZEROPS * 176
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DC.W OPRFAL-ZEROPS * 177
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DC.W OPPRNI-ZEROPS * 178
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DC.W OPPRNR-ZEROPS * 179
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DC.W OPNOOP-ZEROPS * 180
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DC.W OPSAVE-ZEROPS * 181
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DC.W OPREST-ZEROPS * 182
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DC.W OPRSTT-ZEROPS * 183
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DC.W OPRSTA-ZEROPS * 184
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DC.W OPFSTA-ZEROPS * 185
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DC.W OPQUIT-ZEROPS * 186
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DC.W OPCRLF-ZEROPS * 187
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DC.W OPUSL-ZEROPS * 188
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DC.W OPVERI-ZEROPS * 189
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DC.W OPERR-ZEROPS * 190
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DC.W OPERR-ZEROPS * 191
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ONEOPS DC.W OPQZER-ONEOPS * 128
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DC.W OPQNEX-ONEOPS * 129
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DC.W OPQFIR-ONEOPS * 130
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DC.W OPLOC-ONEOPS * 131
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DC.W OPPTSI-ONEOPS * 132
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DC.W OPINC-ONEOPS * 133
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DC.W OPDEC-ONEOPS * 134
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DC.W OPPRNB-ONEOPS * 135
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DC.W OPCAL1-ONEOPS * 136 EZIP
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DC.W OPREMO-ONEOPS * 137
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DC.W OPPRND-ONEOPS * 138
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DC.W OPRETU-ONEOPS * 139
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DC.W OPJUMP-ONEOPS * 140
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DC.W OPPRIN-ONEOPS * 141
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DC.W OPVALU-ONEOPS * 142
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DC.W OPBCOM-ONEOPS * 143
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TWOOPS:
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EXTOPS: DC.W OPERR-EXTOPS * 0
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DC.W OPQEQU-EXTOPS * 1
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DC.W OPQLES-EXTOPS * 2
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DC.W OPQGRT-EXTOPS * 3
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DC.W OPQDLE-EXTOPS * 4
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DC.W OPQIGR-EXTOPS * 5
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DC.W OPQIN-EXTOPS * 6
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DC.W OPBTST-EXTOPS * 7
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DC.W OPBOR-EXTOPS * 8
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DC.W OPBAND-EXTOPS * 9
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DC.W OPQFSE-EXTOPS * 10
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DC.W OPFSET-EXTOPS * 11
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DC.W OPFCLE-EXTOPS * 12
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DC.W OPSET-EXTOPS * 13
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DC.W OPMOVE-EXTOPS * 14
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DC.W OPGET-EXTOPS * 15
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DC.W OPGETB-EXTOPS * 16
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DC.W OPGETP-EXTOPS * 17
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DC.W OPGTPT-EXTOPS * 18
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DC.W OPNEXT-EXTOPS * 19
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DC.W OPADD-EXTOPS * 20
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DC.W OPSUB-EXTOPS * 21
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DC.W OPMUL-EXTOPS * 22
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DC.W OPDIV-EXTOPS * 23
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DC.W OPMOD-EXTOPS * 24
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DC.W OPCAL2-EXTOPS * 25 EZIP
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DC.W OPERR-EXTOPS * 26
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DC.W OPERR-EXTOPS
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DC.W OPERR-EXTOPS
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DC.W OPERR-EXTOPS
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DC.W OPERR-EXTOPS
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DC.W OPERR-EXTOPS
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DC.W OPCALL-EXTOPS * 224
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DC.W OPPUT-EXTOPS * 225
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DC.W OPPUTB-EXTOPS * 226
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DC.W OPPUTP-EXTOPS * 227
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DC.W OPREAD-EXTOPS * 228
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DC.W OPPRNC-EXTOPS * 229
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DC.W OPPRNN-EXTOPS * 230
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DC.W OPRAND-EXTOPS * 231
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DC.W OPPUSH-EXTOPS * 232
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DC.W OPPOP-EXTOPS * 233
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DC.W OPSPLT-EXTOPS * 234
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DC.W OPSCRN-EXTOPS * 235
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DC.W OPXCAL-EXTOPS * 236 EZIP
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DC.W OPCLEAR-EXTOPS * 237 EZIP
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DC.W OPERASE-EXTOPS * 238 EZIP
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DC.W OPCURS-EXTOPS * 239 EZIP
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DC.W OPCURG-EXTOPS * 240 EZIP
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DC.W OPATTR-EXTOPS * 241 EZIP
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DC.W OPBUFO-EXTOPS * 242 EZIP
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DC.W OPDIRO-EXTOPS * 243 EZIP
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DC.W OPDIRI-EXTOPS * 244 EZIP
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DC.W OPSOUND-EXTOPS * 245 EZIP
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DC.W OPINPUT-EXTOPS * 246 EZIP
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DC.W OPINTBL-EXTOPS * 247 EZIP
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DC.W OPERR-EXTOPS
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DC.W OPERR-EXTOPS
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DC.W OPERR-EXTOPS * 250
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DC.W OPERR-EXTOPS
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DC.W OPERR-EXTOPS
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DC.W OPERR-EXTOPS
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DC.W OPERR-EXTOPS
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DC.W OPERR-EXTOPS * 255
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PAGE
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* ----------------------------------------------------------------------------
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* STRING FUNCTIONS
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* ----------------------------------------------------------------------------
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* ZSTR CHARACTER CONVERSION VECTOR
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SECTION ZDATA
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ZCHRS DC.B 'abcdefghijklmnopqrstuvwxyz' * CHAR SET 1
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DC.B 'ABCDEFGHIJKLMNOPQRSTUVWXYZ' * CHAR SET 2
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DC.B ' 0123456789.,!?_#' * CHAR SET 3
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DC.B $27,$22 * <'>,<">
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DC.B '/\-:()'
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DC.B 0 * ASCIZ
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SECTION ZCODE
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* OUTPUT A ZSTR, BLOCK-POINTER IN D0, BYTE-POINTER IN D1
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* RETURN UPDATED POINTER
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PUTSTR MOVEM.L D2-D5,-(SP)
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CLR.W D4 * TEMP CS STARTS AT 0
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CLR.W D5 * PERM CS STARTS AT 0
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PSX1 BSR GETWRD * GET NEXT STRING WORD
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MOVEM.W D0-D2,-(SP) * SAVE POINTER & COPY OF STRING WORD
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MOVEQ #2,D3 * 3 BYTES IN WORD
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PSX2 MOVE.W D2,-(SP) * PUSH CURRENT BYTE
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ASR.W #5,D2 * SHIFT TO NEXT BYTE
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DBF D3,PSX2 * LOOP UNTIL DONE
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MOVEQ #2,D3 * RETRIEVE THE 3 BYTES ...
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PSX3 MOVE.W (SP)+,D2 * GET NEXT BYTE
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ANDI.W #$001F,D2 * CLEAR UNWANTED BITS
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TST.W D4 * IN WORD MODE? (NEGATIVE D4)
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BPL.S PSX4 * NO
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ASL.W #1,D2 * YES, CALCULATE WORD OFFSET
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MOVE.L WRDTAB(A6),A0 * GET WORD TABLE POINTER
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ADD.W WRDOFF(A6),D2 * USE PROPER 32 WORD BLOCK
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ADDA.W D2,A0 * INDEX INTO WORD TABLE
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BSR GTAWRD * GET A POINTER TO THE WORD ITSELF
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BSR BSPLIT * SPLIT IT
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BSR PUTSTR * AND PRINT IT
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BRA PSX15 * CONTINUE WHERE WE LEFT OFF WITH TEMP CS RESET
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PSX4 CMPI.W #3,D4 * CS 3 (ASCII MODE) SELECTED?
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BLT.S PSX6 * NO, NORMAL CS
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BGT.S PSX5 * NO, BUT WE'RE ALREADY IN ASCII MODE
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BSET #14,D4 * YES (MAKE D4 LARGE POSITIVE)
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MOVE.B D2,D4 * SAVE HIGH-ORDER ASCII BITS (2) HERE
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BRA.S PSX16 * AND GO GET NEXT BYTE
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PSX5 ANDI.W #$0003,D4 * EXTRACT PREVIOUSLY SAVED HIGH-ORDER BITS
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ASL.W #5,D4 * POSITION THEM
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OR.W D2,D4 * OR IN LOW-ORDER BITS
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MOVE.W D4,D0
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BRA.S PSX14 * GO PRINT THE CHARACTER
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PSX6 CMPI.W #6,D2 * SPECIAL CODE (0 TO 5)?
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BLT.S PSX9 * YES, SPACE, WORD, OR SHIFT
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CMPI.W #2,D4 * MIGHT ALSO BE SPECIAL IF IN CS 2
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BNE.S PSX8 * BUT WE'RE NOT
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CMPI.W #7,D2 * CS 2, SPECIAL CODE FOR CRLF?
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BEQ.S PSX7 * YES
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BGT.S PSX8 * NO, NOT ASCII MODE, EITHER?
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ADDQ.W #1,D4 * YES IT IS, SWITCH TO ASCII MODE (CS 3)
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BRA.S PSX16 * AND GO GET NEXT BYTE
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PSX7 BSR PUTNEW * CRLF REQUESTED, DO A NEWLINE
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BRA.S PSX15
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PSX8 MOVE.W D4,D1 * NORMAL CHARACTER, GET CS
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MULU #26,D1 * CALCULATE OFFSET FOR THIS CS
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ADD.W D2,D1 * ADD IN CHARACTER OFFSET (+6)
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LEA ZCHRS,A0
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MOVE.B -6(A0,D1.W),D0 * GET THE CHARACTER FROM CONVERSION VECTOR
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BRA.S PSX14 * GO PRINT IT
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PSX9 TST.W D2 * IS IT A SPACE?
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BNE.S PSX10 * NO
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MOVEQ #32,D0 * YES, GO PRINT A SPACE
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BRA.S PSX14
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PSX10 CMPI.W #3,D2 * IS IT A WORD?
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BGT.S PSX11 * NO, MUST BE A SHIFT
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BSET #15,D4 * SWITCH TO WORD MODE (NEG D4) FOR NEXT BYTE
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SUBQ.W #1,D2 * CALCULATE WORD-TABLE BLOCK OFFSET
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ASL.W #6,D2 * 64 BYTES IN A BLOCK
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MOVE.W D2,WRDOFF(A6) * SAVE IT AND LOOP
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BRA.S PSX16
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PSX11 SUBQ.W #3,D2 * CALCULATE NEW CS
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TST.W D4 * TEMPORARY SHIFT (FROM CS 0)?
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BNE.S PSX12 * NO
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MOVE.W D2,D4 * YES, JUST SAVE NEW TEMP CS
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BRA.S PSX16
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PSX12 CMP.W D2,D4 * IS THIS THE CURRENT CS?
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BEQ.S PSX13 * YES, DO A PERM SHIFT TO IT
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CLR.W D4 * OTHERWISE, PERM SHIFT TO CS 0
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PSX13 MOVE.W D4,D5 * TEMP AND PERM CS'S ARE THE SAME NOW
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BRA.S PSX16
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PSX14 BSR PUTCHR * OUTPUT THE CHARACTER
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PSX15 MOVE.W D5,D4 * RESET TEMP CS TO PERM CS
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PSX16 DBF D3,PSX3 * LOOP FOR NEXT BYTE
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MOVEM.W (SP)+,D0-D2 * RESTORE POINTERS & ORIGINAL STRING WORD
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TST.W D2 * END-OF-STRING (HIGH BIT SET)?
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BPL PSX1 * NO, GO GET NEXT WORD
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MOVEM.L (SP)+,D2-D5 * YES, CLEAN UP & RETURN UPDATED POINTER
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RTS
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* GIVEN AN ASCII CHARACTER IN D0, RETURN THE CHARACTER SET # IN D0
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CHRCS TST.B D0 * IS THIS A NULL?
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BNE.S CHRCX1 * NO
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MOVEQ #3,D0 * YES, RETURN DUMMY CS NUMBER
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BRA.S CHRCX4
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CHRCX1 CMPI.B #'a',D0 * LOWERCASE CHAR?
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BLT.S CHRCX2 * NO
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CMPI.B #'z',D0
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BGT.S CHRCX2 * NO
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CLR.W D0 * YES, RETURN CS 0
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BRA.S CHRCX4
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CHRCX2 CMPI.B #'A',D0 * UPPERCASE CHAR?
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BLT.S CHRCX3 * NO
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CMPI.B #'Z',D0
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BGT.S CHRCX3 * NO
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MOVEQ #1,D0 * YES, RETURN CS 1
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BRA.S CHRCX4
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CHRCX3 MOVEQ #2,D0 * OTHERWISE CALL IT CS 2
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CHRCX4 RTS
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|
|
* GIVEN AN ASCII CHARACTER IN D0, RETURN ZSTR BYTE VALUE IN D0 (6 TO 31, OR 0)
|
|
|
|
CHRBYT LEA ZCHRS,A0 * POINT TO CONVERSION VECTOR
|
|
|
|
CHRBX1 CMP.B (A0)+,D0 * FOUND THE CHARACTER?
|
|
BEQ.S CHRBX2 * YES
|
|
TST.B (A0) * END OF STRING?
|
|
BNE.S CHRBX1 * NO, CONTINUE SEARCH
|
|
CLR.W D0 * YES, RETURN ZERO FOR FAILURE
|
|
BRA.S CHRBX4
|
|
|
|
CHRBX2 MOVE.L A0,D0 * CALCULATE OFFSET OF CHAR INTO VECTOR
|
|
LEA ZCHRS,A0
|
|
SUB.L A0,D0
|
|
ADDQ.W #5,D0 * ADJUST OFFSET SO FIRST CHAR IS 6
|
|
|
|
CHRBX3 CMPI.W #32,D0 * IN BASE CODE RANGE (6-31)?
|
|
BLT.S CHRBX4 * YES
|
|
SUBI.W #26,D0 * SUBTRACT MULTIPLES OF 26 UNTIL BASE CODE
|
|
BRA.S CHRBX3
|
|
CHRBX4 RTS
|
|
|
|
|
|
* GIVEN UP TO 6 (EZIP 9) ASCIZ CHARACTERS, BUFFER POINTER IN A1,
|
|
* CONVERT THEM TO A TWO (EZIP THREE) WORD ZSTR, BUFFER POINTER IN A0
|
|
|
|
PADCHR EQU 5 * ZSTR PADDING CHAR (SHIFT 2)
|
|
|
|
ZWORD MOVEM.L D1-D2/A2,-(SP)
|
|
MOVE.L A0,A2
|
|
MOVE.W #VCHARS,D2 * NUMBER OF PACKED CHARS IN A ZSTR (6 OR 9)
|
|
|
|
ZWX1 CLR.W D1
|
|
MOVE.B (A1)+,D1 * GET NEXT CHARACTER, END-OF-STRING?
|
|
BEQ.S ZWX4 * YES
|
|
|
|
MOVE.W D1,D0
|
|
BSR CHRCS * FIND THE CS NUMBER FOR THIS CHAR
|
|
TST.W D0 * CS 0?
|
|
BEQ.S ZWX2 * YES
|
|
ADDQ.W #3,D0 * NO, CALCULATE TEMP SHIFT BYTE
|
|
MOVE.W D0,-(SP) * SAVE THE SHIFT BYTE
|
|
SUBQ.W #1,D2 * REDUCE BYTE COUNT, DONE YET?
|
|
BEQ.S ZWX6 * YES
|
|
|
|
ZWX2 MOVE.W D1,D0
|
|
BSR CHRBYT * FIND THE PROPER BYTE VALUE FOR THIS CHAR
|
|
TST.W D0 * IN NORMAL CS'S?
|
|
BNE.S ZWX3 * YES
|
|
|
|
MOVEQ #6,D0 * NO, USE ASCII SHIFT
|
|
MOVE.W D0,-(SP)
|
|
SUBQ.W #1,D2 * DONE YET?
|
|
BEQ.S ZWX6 * YES
|
|
|
|
MOVE.W D1,D0 * NO, SAVE HIGH-ORDER ASCII BITS (3)
|
|
ASR.W #5,D0
|
|
MOVE.W D0,-(SP)
|
|
SUBQ.W #1,D2 * DONE YET?
|
|
BEQ.S ZWX6 * YES
|
|
|
|
MOVE.W D1,D0 * NO, SAVE LOW-ORDER ASCII BITS (5)
|
|
ANDI.W #$001F,D0
|
|
ZWX3 MOVE.W D0,-(SP) * SAVE THIS BYTE
|
|
|
|
SUBQ.W #1,D2 * AND LOOP UNTIL ZWORD FULL
|
|
BNE ZWX1
|
|
BRA.S ZWX6
|
|
|
|
ZWX4 MOVE.W #PADCHR,-(SP) * END OF STRING, SAVE A PAD BYTE
|
|
SUBQ.W #1,D2 * LOOP UNTIL ZSTR FULL
|
|
BNE.S ZWX4
|
|
|
|
*** BUILD A ZSTR FROM THE SAVED BYTES ...
|
|
|
|
ZWX6 MOVE.W #VCHARS*2,D2 * 6 OR 9 CHARS (WORDS) ON STACK
|
|
MOVE.L SP,A0 * DON'T DISTURB SP YET (IN CASE OF INTERRUPTS)
|
|
ADDA.W D2,A0
|
|
MOVE.W #VCHARS/3,D1 * 2 OR 3 TIMES THROUGH LOOP
|
|
|
|
ZWX7 MOVE.W -(A0),D0
|
|
ASL.W #5,D0
|
|
OR.W -(A0),D0
|
|
ASL.W #5,D0
|
|
OR.W -(A0),D0
|
|
MOVE.W D0,(A2)+ * STORE A PACKED ZWORD IN RETURN BUFFER
|
|
|
|
SUBQ.W #1,D1
|
|
BNE.S ZWX7 * GO FOR NEXT
|
|
|
|
BSET #7,-2(A2) * SET HIGH-ORDER BIT IN LAST ZWORD
|
|
ADDA.W D2,SP * AND FLUSH THE STACK
|
|
|
|
MOVEM.L (SP)+,D1-D2/A2
|
|
RTS
|
|
|
|
|
|
PAGE
|
|
*--------------------------------------------------------------------------
|
|
* GENERALIZED OUTPUT FOLDING ROUTINE
|
|
*--------------------------------------------------------------------------
|
|
|
|
* THE QUECHR ROUTINE IS CALLED WITH A POINTER TO A STRUCTURE CONTAINING
|
|
* THE VARIABLES BELOW. THIS ARRANGEMENT ALLOWS FOR THE EXISTANCE OF MORE THAN
|
|
* ONE STRUCTURE, USEFUL IF DISPLAYED TEXT AND SCRIPTED TEXT ARE TO FOLD AT
|
|
* DIFFERENT POINTS.
|
|
|
|
* THE STRUCTURE IDENTIFIES TWO ACTION ROUTINES. THE OUTPUT FUNCTION
|
|
* DUMPS THE BUFFER WHEN IT BECOMES FULL. THE SIZE FUNCTION ALLOWS FOR THE
|
|
* HANDLING OF PROPORTIONALLY SPACED TEXT.
|
|
|
|
* THE LAST TWO VARIABLES ARE CURRENTLY IGNORED, BUT MIGHT BE USEFUL
|
|
* FOR IMPLEMENTING RECALCULATION OF THE FOLD POINTS FOR A PARAGRAPH OF TEXT,
|
|
* AS WHEN A WINDOW CHANGES SIZE.
|
|
|
|
|
|
* DATA STRUCTURE FOR QUEUE-PARAMETERS BLOCK
|
|
|
|
BUFPTR EQU 0 * START OF BUFFER
|
|
BUFSIZ EQU 4 * MAXIMUM UNITS IN BUFFER
|
|
|
|
NXTPTR EQU 6 * CURRENT POSITION WITHIN BUFFER
|
|
CURSIZ EQU 10 * CURRENT UNITS IN BUFFER
|
|
|
|
SIZFUN EQU 12 * GIVEN A CHAR, RETURNS UNIT SIZE
|
|
OUTFUN EQU 16 * GIVEN BUFPTR & ENDPTR, DUMPS BUFFER, ADDS CR
|
|
RETFUN EQU 20 * (UNUSED -- THIS SHOULD ADD THE CR)
|
|
|
|
DUMPED EQU 24 * WAS BUFFER EMPTIED (WITHOUT CR) BEFORE FULL?
|
|
AUTOCR EQU 25 * APPEND A CR TO EACH BUFFER DUMP? *** YES
|
|
KEEPSP EQU 26 * DON'T DISCARD TRAILING SPACE? *** NO
|
|
|
|
QPLEN EQU 28 * LENGTH OF BLOCK (ALWAYS EVEN)
|
|
|
|
|
|
* ALLOCATE AND INITIALIZE A QUEUE PARAMETER BLOCK,
|
|
* D1 IS MAXIMUM SIZE OF BUFFER (IN BYTES), D2 IS INITIAL UNIT SIZE
|
|
* A1 POINTS TO LINE OUTPUT FUNCTION, A2 POINTS TO UNIT SIZE FUNCTION
|
|
* RETURN BLOCK POINTER IN A0
|
|
|
|
INITQP MOVE.W D1,D0
|
|
ADD.W #QPLEN,D0 * TOTAL SPACE TO ALLOCATE
|
|
EXT.L D0
|
|
BSR GETMEM * GET IT
|
|
|
|
MOVE.L A0,D0 * PARAMETERS BLOCK WILL START HERE
|
|
ADD.L #QPLEN,D0
|
|
MOVE.L D0,BUFPTR(A0) * LINE BUFFER STARTS HERE
|
|
MOVE.L D0,NXTPTR(A0) * ALSO CURRENT POINTER
|
|
|
|
MOVE.W D2,BUFSIZ(A0) * UNIT CAPACITY OF BUFFER
|
|
CLR.W CURSIZ(A0) * ALWAYS EMPTY INITIALLY
|
|
|
|
MOVE.L A1,OUTFUN(A0) * INITIALIZE LINE OUTPUT FUNCTION
|
|
MOVE.L A2,SIZFUN(A0) * INITIALIZE CHAR SIZE FUNCTION
|
|
|
|
CLR.B DUMPED(A0) * THIS ONE IS SET ONLY BY PUTLIN
|
|
RTS * RETURN THE POINTER IN A0
|
|
|
|
|
|
* QUEUE THE CHAR IN D0 FOR OUTPUT, A0 POINTS TO QUEUE-PARAMETERS BLOCK
|
|
|
|
QUECHR MOVEM.L D4/A1-A4,-(SP)
|
|
MOVE.W D0,D4
|
|
MOVE.L A0,A4
|
|
|
|
MOVE.W CURSIZ(A4),D0
|
|
CMP.W BUFSIZ(A4),D0 * BUFFER FULL YET?
|
|
BLT QCX8 * NO
|
|
*** BGT QCX0 * OVERFULL (DEQUE THE LAST CHAR AND REENTER)
|
|
|
|
CMPI.B #32,D4 * YES, BUT DID A SPACE CAUSE OVERFLOW?
|
|
BNE.S QCX1 * NO
|
|
|
|
MOVE.L NXTPTR(A4),D0 * YES, JUST PRINT THE WHOLE BUFFER
|
|
MOVE.L BUFPTR(A4),A0
|
|
|
|
MOVE.L OUTFUN(A4),A3
|
|
JSR (A3)
|
|
|
|
CLR.W CURSIZ(A4) * RESET LENGTH COUNTER
|
|
MOVE.L BUFPTR(A4),NXTPTR(A4) * RESET CURRENT CHAR POINTER
|
|
CLR.B DUMPED(A4) * STARTING A FRESH LINE
|
|
BRA.S QCX9 * EXIT, IGNORING SPACE
|
|
|
|
* FOLDING ROUTINE, SEARCH FOR MOST-RECENT SPACE ...
|
|
|
|
QCX1 MOVE.L BUFPTR(A4),A1 * BEGINNING OF BUFFER
|
|
MOVE.L NXTPTR(A4),A2 * END OF BUFFER (+1)
|
|
BRA.S QCX2A * ALLOW FOR EMPTY [DUMPED] BUFFER
|
|
|
|
QCX2 CMPI.B #32,-(A2) * SEARCH FOR SPACE BACKWARDS FROM END
|
|
BEQ.S QCX4 * FOUND ONE
|
|
QCX2A CMPA.L A1,A2 * REACHED BEGINNING OF BUFFER?
|
|
BGT QCX2 * NOT YET
|
|
|
|
* NO SPACES FOUND, DUMP WHOLE BUFFER ...
|
|
|
|
QCX3 TST.B DUMPED(A4) * BUT WAS THIS BUFFER ALREADY PARTLY EMPTIED?
|
|
BNE.S QCX5 * YES, CARRY EVERYTHING OVER TO NEXT LINE
|
|
|
|
MOVE.L NXTPTR(A4),A2 * OTHERWISE, OUTPUT EVERYTHING
|
|
BRA.S QCX5
|
|
|
|
* SPACE WAS FOUND, DUMP THE BUFFER (THROUGH SPACE) ...
|
|
|
|
QCX4 MOVE.L A2,A0 * POINTER TO THE SPACE
|
|
ADDQ.L #1,A2 * POINTER PAST THE SPACE
|
|
|
|
CMPA.L A1,A0 * DEGENERATE CASE WITH SPACE AT BUFPTR?
|
|
BEQ.S QCX3 * YES, OUTPUT WHOLE LINE
|
|
|
|
QCX5 MOVE.L A2,D0 * LAST CHAR TO PRINT (+1)
|
|
MOVE.L A1,A0 * START OF BUFFER
|
|
|
|
MOVE.L OUTFUN(A4),A3 * GO DUMP IT, ADDING A CR
|
|
JSR (A3)
|
|
|
|
* SHIFT ANY REMAINING CHARS TO FRONT OF BUFFER ...
|
|
|
|
CLR.W CURSIZ(A4) * ZERO THE UNIT COUNT
|
|
CLR.B DUMPED(A4) * START WITH A FRESH BUFFER
|
|
BRA.S QCX7
|
|
|
|
QCX6 MOVE.B (A2)+,D0
|
|
MOVE.B D0,(A1)+ * COPY NEXT CHAR TO BEGINNING OF BUF
|
|
|
|
MOVE.L SIZFUN(A4),A0 * CHAR STILL IN D0
|
|
JSR (A0)
|
|
ADD.W D0,CURSIZ(A4) * UPDATE THE UNIT COUNT
|
|
|
|
QCX7 CMPA.L NXTPTR(A4),A2 * ANY MORE CHARS AFTER SPACE?
|
|
BLT QCX6 * YES
|
|
MOVE.L A1,NXTPTR(A4) * NO, STORE NEW CURRENT POINTER HERE
|
|
|
|
* FINALLY, STORE THE NEW CHAR AND EXIT ...
|
|
|
|
QCX8 MOVE.L NXTPTR(A4),A0
|
|
MOVE.B D4,(A0)+ * STORE THE NEW CHARACTER IN BUFFER
|
|
MOVE.L A0,NXTPTR(A4) * AND UPDATE POINTER
|
|
|
|
TST.W WIND1(A6) * BUT IF WE'RE IN SPLIT SCREEN,
|
|
BNE.S QCX9 * DON'T TOUCH COUNTER (SEE ALSO OPBUFO)
|
|
|
|
MOVE.W D4,D0
|
|
MOVE.L SIZFUN(A4),A0
|
|
JSR (A0) * GET UNIT SIZE OF NEW CHAR
|
|
ADD.W D0,CURSIZ(A4) * AND UPDATE COUNTER
|
|
|
|
QCX9 MOVEM.L (SP)+,D4/A1-A4
|
|
RTS
|
|
|
|
*--------------------------------------------------------------------------
|
|
* MAIN OUTPUT HANDLER
|
|
*--------------------------------------------------------------------------
|
|
|
|
* !ALL! OUTPUT GENERATED BY THE GAME (AND THE USER) SHOULD BE CHANNELED
|
|
* THROUGH THE FOLLOWING TWO ROUTINES, WHICH REDIRECT IT APPROPRIATELY.
|
|
|
|
|
|
* OUTPUT A NEWLINE
|
|
|
|
PUTNEW MOVEQ #13,D0 * JUST FALL THROUGH WITH A CR
|
|
|
|
* OUTPUT THE CHAR IN D0 (TO THE REQUESTED DEVICES)
|
|
|
|
PUTCHR CMPI.B #9,D0 * TAB? (OLD ZORK BUG, DISPLAYS GARBAGE)
|
|
BNE.S PCX1
|
|
MOVEQ #32,D0 * YES, MAP TO A SPACE
|
|
PCX1
|
|
|
|
*** STATUS LINE OUTPUT (ZIP INTERNAL FUNCTION ONLY) ...
|
|
|
|
IFEQ CZIP
|
|
TST.W VOSTAT(A6) * SPECIAL OUTPUT TO SL HANDLER?
|
|
BNE PUTSL * YES (ABORT PUTCHR)
|
|
ENDC
|
|
|
|
*** TABLE OUTPUT ...
|
|
|
|
IFEQ EZIP
|
|
TST.W VOTABL(A6) * TABLE OUTPUT?
|
|
BNE TABCHR * YES (ABORT PUTCHR PER "DIROUT" SPEC)
|
|
ENDC
|
|
|
|
MOVE.W D0,-(SP) * OTHERWISE, SAVE THE CHAR HERE
|
|
|
|
*** SCRIPT (BEFORE SCREEN, TO PERMIT ERROR HANDLING) ...
|
|
|
|
TST.W WIND1(A6) * BUT ARE WE IN WINDOW 1?
|
|
BNE.S PCX2 * YES, TEMPORARILY AVOID SCRIPTING
|
|
|
|
IFEQ EZIP
|
|
TST.W VOPRNT(A6) * SCRIPTING ACTIVE?
|
|
ENDC
|
|
IFEQ CZIP
|
|
BSR TSTSCR * CHECK FOR SCRIPTING REQUEST -- ACTIVE?
|
|
ENDC
|
|
BEQ.S PCX2 * NO
|
|
|
|
MOVE.W (SP),D0 * SCRIPT THIS CHAR
|
|
BSR SCRCHR
|
|
|
|
*** SCREEN DISPLAY ...
|
|
|
|
PCX2 TST.W VOCONS(A6) * CONSOLE OUTPUT ACTIVE?
|
|
BEQ.S PCX3 * NO
|
|
|
|
MOVE.W (SP),D0 * YES, DISPLAY THE CHAR
|
|
BSR QDCHR
|
|
|
|
*** FILE OUTPUT ...
|
|
|
|
PCX3 NOP * NOT IMPLEMENTED
|
|
|
|
TST.W (SP)+ * FLUSH CHAR FROM STACK
|
|
RTS
|
|
|
|
|
|
*--------------------------------------------------------------------------
|
|
* TERMINAL DISPLAY FUNCTIONS
|
|
*--------------------------------------------------------------------------
|
|
|
|
* QUEUE/DISPLAY THE CHAR IN D0
|
|
|
|
QDCHR TST.W VOBUFF(A6) * IS BUFFERING TURNED OFF?
|
|
BEQ OUTCHR * YES, GO TO SCREEN (THIS HANDLES CR'S ALSO)
|
|
|
|
CMPI.B #13,D0 * CR?
|
|
BEQ.S NEWLIN * YES, DUMP THE BUFFER
|
|
|
|
MOVE.L DQUE(A6),A0 * OTHERWISE, GO QUEUE IT
|
|
BRA QUECHR
|
|
|
|
* GO TO NEW LINE, OUTPUTTING CURRENT BUFFER
|
|
* (THIS ROUTINE NOW CALLED ONLY FROM THE PRECEEDING ROUTINE)
|
|
|
|
NEWLIN MOVE.L A4,-(SP)
|
|
MOVE.L DQUE(A6),A4 * SCREEN BUFFER
|
|
|
|
MOVE.L BUFPTR(A4),A0 * START OF LINE
|
|
MOVE.L NXTPTR(A4),D0 * END OF CURRENT LINE
|
|
BSR LINOUT * CHECK "MORE", OUTPUT LINE, ADD A CR
|
|
|
|
MOVE.L BUFPTR(A4),NXTPTR(A4) * RESET CHARACTER POINTER
|
|
CLR.W CURSIZ(A4) * RESET UNIT COUNT
|
|
CLR.B DUMPED(A4) * NO OUTPUT ON NEW LINE YET
|
|
|
|
MOVE.L (SP)+,A4
|
|
RTS
|
|
|
|
* OUTPUT CURRENT BUFFER, WITHOUT A NEWLINE
|
|
* (ASSUMES SOMETHING LIKE OPREAD WILL SUPPLY THE NEWLINE)
|
|
|
|
PUTLIN MOVE.L DQUE(A6),A0
|
|
CLR.W CURSIZ(A0) * RESET UNIT COUNT (BUFFER EMPTY)
|
|
|
|
* ENTER HERE IF BUFFERING WILL LATER RESUME FROM CURRENT POINT
|
|
|
|
PUTLIN1 MOVE.L A4,-(SP)
|
|
MOVE.L DQUE(A6),A4 * SCREEN BUFFER
|
|
|
|
MOVE.L BUFPTR(A4),A0 * START OF LINE
|
|
MOVE.L NXTPTR(A4),D0 * END OF CURRENT LINE
|
|
BSR BUFOUT * OUTPUT IT (NO "MORE", NO CR)
|
|
|
|
MOVE.L BUFPTR(A4),NXTPTR(A4) * RESET CHARACTER POINTER
|
|
MOVE.B #1,DUMPED(A4) * REMEMBER BUFFER IS PARTLY DUMPED
|
|
MOVE.L (SP)+,A4
|
|
RTS
|
|
|
|
|
|
* INPUT A CHARACTER FROM TERMINAL
|
|
|
|
GETCHR BRA INCHR * JUST GET IT
|
|
|
|
|
|
*--------------------------------------------------------------------------
|
|
* SCRIPT BUFFERING
|
|
*--------------------------------------------------------------------------
|
|
|
|
* QUEUE THE CHAR IN D0 FOR SCRIPTING
|
|
|
|
SCRCHR CMPI.B #13,D0 * CR?
|
|
BEQ.S SCRLIN * YES, GO DUMP SCRIPT BUFFER
|
|
|
|
MOVE.L SQUE(A6),A0 * SCRIPTING PARAMETERS BLOCK
|
|
BRA QUECHR * GO QUEUE IT
|
|
|
|
* SCRIPT A NEWLINE, OUTPUTTING CURRENT SCRIPT BUFFER
|
|
|
|
SCRLIN MOVE.L A4,-(SP)
|
|
MOVE.L SQUE(A6),A4 * SCRIPTING PARAMETERS BLOCK
|
|
|
|
MOVE.L BUFPTR(A4),A0 * START OF LINE
|
|
MOVE.L NXTPTR(A4),D0 * END OF CURRENT LINE
|
|
BSR SCROUT * OUTPUT LINE, ADD A CR ...
|
|
|
|
MOVE.L BUFPTR(A4),NXTPTR(A4) * RESET CHARACTER POINTER
|
|
CLR.W CURSIZ(A4) * RESET UNIT COUNT
|
|
|
|
MOVE.L (SP)+,A4
|
|
RTS
|
|
|
|
* SCRIPT THE USER INPUT LINE, START IN A0, END IN D0
|
|
* (WAIT UNTIL USER INPUT IS FINISHED TO AVOID PROBLEMS WITH BACKSPACES)
|
|
|
|
SCRINP MOVEM.L A1/D1,-(SP)
|
|
MOVE.L A0,A1 * PROTECT ARGS
|
|
MOVE.L D0,D1
|
|
|
|
IFEQ EZIP
|
|
TST.W VOPRNT(A6) * SCRIPTING?
|
|
ENDC
|
|
IFEQ CZIP
|
|
BSR TSTSCR * CHECK FOR SCRIPT REQUEST -- ACTIVE?
|
|
ENDC
|
|
BEQ.S SCRIX3 * NO, EXIT
|
|
|
|
SUB.L A1,D1 * LENGTH OF INPUT -- ANYTHING?
|
|
BEQ.S SCRIX2 * NO, JUST DO THE CR
|
|
|
|
SCRIX1 MOVE.B (A1)+,D0 * SCRIPT NEXT CHAR
|
|
BSR SCRCHR * (GO THRU BUFFER SO WRAPPING IS CORRECT)
|
|
SUBQ.W #1,D1
|
|
BGT SCRIX1
|
|
|
|
SCRIX2 MOVEQ #13,D0 * ALWAYS END WITH A CR
|
|
BSR SCRCHR
|
|
|
|
SCRIX3 MOVEM.L (SP)+,D1/A1
|
|
RTS
|
|
|
|
|
|
PAGE
|
|
* ----------------------------------------------------------------------------
|
|
* PAGING ROUTINES
|
|
* ----------------------------------------------------------------------------
|
|
|
|
* NORMALIZE ZPC & (IF NECESSARY) GET PROPER PAGE
|
|
|
|
NEWZPC MOVE.W ZPC2(A6),D0 * LOW ORDER ZPC
|
|
ASR.W #8,D0 * EXTRACT REQUIRED BLOCK ADJUSTMENT (+ OR -)
|
|
ASR.W #1,D0
|
|
|
|
ADD.W D0,ZPC1(A6) * AND ADJUST HIGH ORDER ZPC
|
|
ANDI.W #$01FF,ZPC2(A6) * NORMALIZE LOW ORDER ZPC
|
|
|
|
* GET THE INDICATED PAGE
|
|
|
|
MOVE.W ZPC1(A6),D0
|
|
CMP.W CURBLK(A6),D0 * HAS THE BLOCK CHANGED?
|
|
BEQ.S NZX4 * NO, EXIT
|
|
MOVE.W D0,CURBLK(A6) * YES, REMEMBER NEW BLOCK
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TST.L CURTAB(A6) * IS OLD PAGE PRELOADED?
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BEQ.S NZX2 * YES
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MOVE.L CURTAB(A6),A0 * NO, RESTORE CURRENT REF TIME FOR OLD PAGE
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MOVE.L RTIME(A6),2(A0)
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NZX2 CMP.W ENDLOD(A6),D0 * IS NEW PAGE PRELOADED?
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BLT.S NZX3 * YES
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BSR GETPAG * NO, GET THE NEW PAGE
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MOVE.L A0,CURPAG(A6) * REMEMBER NEW PAGE POINTER
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MOVE.L LPTAB(A6),A0 * GET NEW TABLE POINTER
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MOVE.L A0,CURTAB(A6) * SAVE THIS POINTER FOR LATER
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MOVE.L #-1,2(A0) * FAKE A HIGH RTIME TO PROTECT ZPC PAGE FOR US
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BRA.S NZX4
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NZX3 BSR BLKBYT * CALCULATE PRELOAD PAGE ADDRESS
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ADD.L BUFFER(A6),D0 * ABSOLUTIZE
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MOVE.L D0,CURPAG(A6) * REMEMBER NEW PAGE POINTER
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CLR.L CURTAB(A6) * ZERO TABLE POINTER MEANS PAGE IS PRELOADED
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NZX4 RTS
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* GET THE PAGE WHOSE NUMBER IS IN D0, RETURN A POINTER TO IT IN A0
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GETPAG CMP.W LPAGE(A6),D0 * IS THIS THE SAME PAGE AS LAST REFERENCED?
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BEQ.S GPX4 * YES, RETURN ITS LOCATION
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MOVE.W D0,LPAGE(A6) * SAVE NEW PAGE NUMBER
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ADDQ.L #1,RTIME(A6) * UPDATE REFERENCE COUNT
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MOVE.L PAGTAB(A6),A0 * PAGE INFORMATION TABLE
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GPX1 CMP.W (A0),D0 * SEARCH FOR DESIRED BLOCK
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BNE.S GPX3 * NOT IT
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CMP.W CURBLK(A6),D0 * FOUND IT, BUT IS IT THE CURRENT ZPC PAGE?
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BEQ.S GPX2 * YES, DON'T TOUCH REF TIME (PAGE IS PROTECTED)
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MOVE.L RTIME(A6),2(A0) * NO, UPDATE ITS REFERENCE TIME
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GPX2 MOVE.L A0,LPTAB(A6) * SAVE THE TABLE POINTER
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MOVE.L A0,D0
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SUB.L PAGTAB(A6),D0 * BUFFER NUMBER x8
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ASL.L #6,D0 * CALCULATE CORE ADDRESS OF PAGE
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ADD.L PAGES(A6),D0
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MOVE.L D0,LPLOC(A6) * SAVE IT
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BRA.S GPX4 * AND RETURN IT
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GPX3 ADDQ.L #8,A0 * SKIP OVER REFERENCE TIME, ETC.
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CMPI.W #-1,(A0) * END OF TABLE?
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BNE.S GPX1 * NO, CONTINUE SEARCH
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* DESIRED PAGE NOT RESIDENT, MUST READ IT FROM DISK
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MOVE.L A1,-(SP)
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BSR FINDPG * FIND AN OLD PAGE
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MOVE.L A0,LPLOC(A6) * SAVE ITS PAGE POINTER
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MOVE.L A1,LPTAB(A6) * SAVE ITS PAGTAB POINTER
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MOVE.W LPAGE(A6),D0 * NEW PAGE NUMBER FOR GETBLK
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MOVE.W D0,(A1)+ * SAVE PAGE NUMBER IN FIRST SLOT
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MOVE.L RTIME(A6),(A1) * SAVE CURRENT REF TIME
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BSR GETBLK * GET THE BLOCK
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MOVE.L (SP)+,A1 * CLEAN UP
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IFEQ DEBUG
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ADDQ.L #1,DBTOT1(A6) * TOTAL PAGE FAULTS
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ENDC
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GPX4 MOVE.L LPLOC(A6),A0 * RETURN THE PAGE POINTER
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RTS
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* FIND A GOOD (LRU) PAGE, RETURN PAGE POINTER IN A0 & PAGTAB POINTER IN A1
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FINDPG MOVE.L PAGTAB(A6),A0
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ADDQ.L #2,A0 * SKIP OVER FIRST PAGE NUMBER
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MOVE.L #-1,D0 * FAKE A BEST-CASE REFERENCE COUNT
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FDPGX1 CMP.L (A0),D0 * COMPARE PREV OLDEST REF TIME WITH THIS ONE
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BLS.S FDPGX2 * STILL THE OLDEST
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MOVE.L (A0),D0 * NEW OLDEST, SAVE THIS REFERENCE COUNT
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MOVE.L A0,A1 * AND PAGTAB LOCATION (+2)
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FDPGX2 ADDQ.L #6,A0 * SKIP OVER REF TIME, ETC.
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CMPI.W #-1,(A0)+ * END OF TABLE?
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BNE.S FDPGX1 * NO
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SUBQ.L #2,A1 * RETURN THE PAGTAB LOCATION HERE
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MOVE.L A1,D0
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SUB.L PAGTAB(A6),D0 * BUFFER NUMBER x8
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ASL.L #6,D0 * CALCULATE CORE ADDRESS OF PAGE
|
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ADD.L PAGES(A6),D0
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MOVE.L D0,A0 * AND RETURN IT HERE
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RTS
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