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38 lines
1.2 KiB
Plaintext
38 lines
1.2 KiB
Plaintext
# asm - assembler and interpreter for simple computer
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# usage: awk -f asm program-file data-files...
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# this is a special version to produce a listing
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BEGIN {
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srcfile = ARGV[1]
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ARGV[1] = "" # remaining files are data
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tempfile = "/tmp/asm.temp"
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n = split("const get put ld st add sub jpos jz j halt", x)
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for (i = 1; i <= n; i++) # create table of op codes
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op[x[i]] = i-1
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# ASSEMBLER PASS 1
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nextmem = 0 # new
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FS = "[ \t]+"
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while (getline <srcfile > 0) {
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input[nextmem] = $0 # new: remember source line
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sub(/#.*/, "") # strip comments
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symtab[$1] = nextmem # remember label location
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if ($2 != "") { # save op, addr if present
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print $2 "\t" $3 >tempfile
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nextmem++
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}
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}
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close(tempfile)
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# ASSEMBLER PASS 2
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nextmem = 0
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while (getline <tempfile > 0) {
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if ($2 !~ /^[0-9]*$/) # if symbolic addr,
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$2 = symtab[$2] # replace by numeric value
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mem[nextmem++] = 1000 * op[$1] + $2 # pack into word
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}
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for (i = 0; i < nextmem; i++) # new: print memory
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printf("%3d: %05d %s\n", i, mem[i], input[i]) # new
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}
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