Aryadev Chavali
05136fdd25
Name assigned to %CONST is the next symbol in stream, not the symbol attached to it.
55 lines
1008 B
NASM
55 lines
1008 B
NASM
;;; factorial.asm: A program that generates the factorials of each
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;;; number from 1 to 20. Using the registers to store `n` and `n!`.
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;; Constants
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;; Choice of 20 was not arbitrary; log(20!) ~= 61 while log(21!) ~=
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;; 65 which means that past 20! results are truncated and therefore
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;; the program produces inaccurate factorials.
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%const limit 20 %end
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;; Setup entrypoint
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global main
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main:
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;; $I -> W[0] = 1, $J -> W[1] = 1
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push.word 1
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mov.word 0
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push.word 1
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mov.word 1
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;; Print `$I: $J`
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loopback:
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push.byte '\t'
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print.char
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push.reg.word 0
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print.word
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push.byte ':'
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print.char
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push.byte ' '
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print.char
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push.reg.word 1
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print.word
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push.byte '\n'
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print.char
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;; $I += 1
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push.reg.word 0
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push.word 1
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plus.word
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mov.word 0
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;; $J *= $I
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push.reg.word 0
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push.reg.word 1
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mult.word
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mov.word 1
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;; IF $I >= $LIMIT ...
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push.word $limit
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push.reg.word 0
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gte.word
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;; THEN jump to `loopback`
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jump.if.byte loopback
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;; ELSE halt
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halt
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