mirror of
https://github.com/DoctorWkt/pdp7-unix.git
synced 2026-01-25 11:47:35 +00:00
tools/a7out: Add the law instruction and change some numeric literals to
named constants.
This commit is contained in:
Warren Toomey
57
tools/a7out
57
tools/a7out
@@ -20,8 +20,8 @@ my $LINK; # Link register
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my $MQ; # MQ register
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# Constants
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my $MAXINT = 0777777; # Biggest unsigned integer
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my $MAXADDR = 017777; # Largest memory address
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use constant MAXINT => 0777777; # Biggest unsigned integer
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use constant MAXADDR => 017777; # Largest memory address
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### Main program ###
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@@ -47,7 +47,7 @@ sub load_code {
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my $filename = shift;
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# Fill all the 8K words in memory with zeroes
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foreach my $i ( 0 .. $MAXADDR ) {
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foreach my $i ( 0 .. MAXADDR ) {
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$Mem[$i] = 0;
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}
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@@ -77,15 +77,15 @@ sub load_code {
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### Copy the arguments into the PDP-7 memory space, and build
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### an array of pointers to these arguments. Build a pointer
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### at $MAXADDR that points at the array.
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### at MAXADDR that points at the array.
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###
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### Each argument string is four words long and space padded if the
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### string is not eight characters long. These are stored below
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### address $MAXADDR. Below this is the count of words in the strings.
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### Address $MAXADDR points at the word count. Graphically (for two arguments):
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### address MAXADDR. Below this is the count of words in the strings.
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### Address MAXADDR points at the word count. Graphically (for two arguments):
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###
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### +------------+
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### +--| | Location 017777 ($MAXADDR)
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### +--| | Location 017777 (MAXADDR)
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### | +------------+
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### | |............|
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### | |............| argv[2]
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@@ -107,10 +107,10 @@ sub set_arguments {
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my $argc= scalar(@ARGV);
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# We now know that argc will appear in memory
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# 4*argc +1 below location $MAXADDR
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# 4*argc +1 below location MAXADDR
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# Set argc to the number of words
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my $addr= $MAXADDR - (4*$argc+1);
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$Mem[ $MAXADDR ] = $addr;
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my $addr= MAXADDR - (4*$argc+1);
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$Mem[ MAXADDR ] = $addr;
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$Mem[ $addr++ ] = $argc*4;
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# Now start saving the arguments
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@@ -149,12 +149,12 @@ sub simulate {
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my $instruction = $Mem[$PC];
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my $opcode = ( $instruction >> 12 ) & 074;
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my $indirect = ( $instruction >> 13 ) & 1;
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my $addr = $instruction & $MAXADDR;
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my $addr = $instruction & MAXADDR;
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# Work out what any indirect address would be
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my $indaddr= ($indirect) ? $Mem[$addr] & $MAXADDR : $addr;
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#dprintf( "PC %06o: instr %06o, op %03o, ind %o, addr %06o ind %06o\n",
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# $PC, $instruction, $opcode, $indirect, $addr, $indaddr );
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my $indaddr= ($indirect) ? $Mem[$addr] & MAXADDR : $addr;
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dprintf( "PC %06o: instr %06o, op %03o, ind %o, addr %06o ind %06o\n",
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$PC, $instruction, $opcode, $indirect, $addr, $indaddr );
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# Simulate the instruction. Each subroutine updates the $PC
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if ( defined( $Oplist{$opcode} ) ) {
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@@ -169,7 +169,7 @@ sub simulate {
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# Debug code: dump memory contents
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sub dump_memory {
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foreach my $i ( 0 .. $MAXADDR ) {
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foreach my $i ( 0 .. MAXADDR ) {
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printf( STDERR "%06o: %06o\n", $i, $Mem[$i] ) if ( $Mem[$i] != 0 );
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}
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}
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@@ -197,7 +197,7 @@ sub tad {
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my ( $instruction, $addr, $indaddr ) = @_;
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dprintf( "PC %06o: tad AC (value %06o) from addr %05o\n",
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$PC, $AC, $indaddr );
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$AC= ($AC + $Mem[$indaddr]) & $MAXINT;
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$AC= ($AC + $Mem[$indaddr]) & MAXINT;
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$PC++;
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}
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@@ -229,7 +229,7 @@ sub special {
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if ( $instruction == 0741100 ) { # spa: skip on positive AC
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dprintf( "PC %06o: spa AC %06o\n", $PC, $AC );
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# Because we are dealing with 18 bits, compare the range
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$PC += ( ($AC >= 0) && ($AC < 0400000) ) ? 2 : 1;
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$PC += ( ($AC >= 0) && ($AC <= MAXINT) ) ? 2 : 1;
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return;
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}
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if ( $instruction == 0741200 ) { # sna: skip on non-zero AC
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@@ -242,6 +242,11 @@ sub special {
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$PC += ( $AC == 0 ) ? 2 : 1;
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return;
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}
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if ( ($instruction >= 0760000) && ($instruction <= MAXINT) ) { # law: load word into AC
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dprintf( "PC %06o: law %06o into AC\n", $PC, $instruction);
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$AC = $instruction;
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$PC++; return;
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}
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printf( STDERR "PC %06o: unknown instruction %06o\n", $PC, $instruction );
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exit(1);
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}
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@@ -287,7 +292,7 @@ sub sys_close {
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# That filehandle is not open, set an error -1 in octal
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if ( !defined( $FD[$fd] ) ) {
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dprint( "close: fd $fd is not open\n");
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$AC = 0777777;
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$AC = MAXINT;
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return;
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}
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close( $FD[$fd] );
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@@ -328,7 +333,7 @@ sub sys_open {
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} else {
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# No filehandle, so it's an error
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dprintf( "open failed: $!\n");
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$AC = 0777777;
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$AC = MAXINT;
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return;
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}
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}
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@@ -344,7 +349,7 @@ sub sys_read {
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my $fd = $AC;
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my $start = $Mem[ $PC + 1 ];
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my $count = $Mem[ $PC + 2 ];
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my $end = ($start + $count - 1) & $MAXADDR;
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my $end = ($start + $count - 1) & MAXADDR;
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die("sys_read: bad start/end addresses $start $end\n") if ($end < $start);
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dprintf( "PC %06o: read: %d words into %o from fd %d\n",
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$PC, $count, $start, $fd );
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@@ -355,7 +360,7 @@ sub sys_read {
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# That filehandle is not open, set an error -1 in octal
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if ( !defined( $FD[$fd] ) ) {
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dprint( "read: fd $fd is not open\n");
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$AC = 0777777;
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$AC = MAXINT;
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return;
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}
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@@ -377,7 +382,7 @@ sub sys_read {
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my $line = <$FH>;
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last if ( !defined($line) ); # No line, leave the loop
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chomp($line);
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$Mem[$addr] = oct($line) & 0777777;
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$Mem[$addr] = oct($line) & MAXINT;
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$count++;
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}
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}
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@@ -397,7 +402,7 @@ sub sys_write {
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my $fd = $AC;
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my $start = $Mem[ $PC + 1 ];
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my $count = $Mem[ $PC + 2 ];
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my $end = ($start + $count - 1) & $MAXADDR;
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my $end = ($start + $count - 1) & MAXADDR;
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die("sys_write: bad start/end addresses $start $end\n") if ($end < $start);
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dprintf( "PC %06o: write: %d words from %o to fd %d\n",
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$PC, $count, $start, $fd );
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@@ -408,7 +413,7 @@ sub sys_write {
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# That filehandle is not open, set an error -1 in octal
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if ( !defined( $FD[$fd] ) ) {
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dprint( "write: fd $fd is not open\n");
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$AC = 0777777;
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$AC = MAXINT;
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return;
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}
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@@ -451,7 +456,7 @@ sub mem2arg {
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foreach (1 .. 4) {
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# Stop if the address leave the 8K word address space
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last if ( $addr > $MAXADDR );
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last if ( $addr > MAXADDR );
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my $word = $Mem[$addr++];
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my $c1 = ( $word >> 9 ) & 0177;
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my $c2 = $word & 0177;
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@@ -472,7 +477,7 @@ sub mem2string {
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while (1) {
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# Stop when the address leave the 8K word address space
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return ($result) if ( $addr > $MAXADDR );
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return ($result) if ( $addr > MAXADDR );
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# Stop when the value there is zero
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my $word = $Mem[$addr];
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