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56 lines
1.5 KiB
Plaintext
56 lines
1.5 KiB
Plaintext
/ u6 -- unix
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read:
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clr u.nread / accumulates number of bytes transmitted
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tst u.count / is number of bytes to be read greater than 0
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bgt 1f / yes, branch
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rts r0 / no, nothing to read; return to caller
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1: ·
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mov r1,-(sp) / save 1—number on stack
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cmp r1,$40. / want to read a special file (1—nodes 1,...,40 are
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/ for special files)
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ble 1f / yes, branch
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jmp dskr / no, jmp to dskr; read file with 1.-node number (:1)
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/ starting at byte ((u.fofp)), read in u.count bytes
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1:
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asl r1 / multiply inode number by 2
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jmp *1f-2(r1)
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1:
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rtty / tty; r1=2
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rppt / ppt; r1=4
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rmem / mem; r1=6
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rrf0 / rf0
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rrk0 / rk0
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rtap / tap0
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rtap / tap1
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rtap / tap2
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rtap / tap3
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rtap / tap4
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rtap / tap5
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rtap / tap6
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rtap / tap7
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rcvt / tty0
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rcvt / tty1
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rcvt / tty2
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rcvt / tty3 ‘
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rcvt / tty4
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rcvt / tty5
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rcvt / tty6
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zcvt / ety7
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rcrd/ crd
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rtty: / read from console tty
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mov tty+[8*ntty]—8+6,r5 / r5 is the address of the 4th word of
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/ of the control and status block _
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tst 2(r5) / for the console tty; this word points to the console
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/ tty bufTer
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bne 1f / 2nd word of console tty buffer contains number
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/ of chars. Is this number non-zero?
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jsr r0,canon; ttych / if 0, call 'canon' to get a line
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/ (120 chars.)
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1:
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tst 2(r5) / is the number of characters zero
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beq ret1 / yes, return to caller via 'ret1'
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movb *4(rS),r1 / no, put character in r1
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inc 4(r5) / 3rd word of console tty buffer points to byte which
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/ contains the next char.
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