48 lines
1.1 KiB
Forth
48 lines
1.1 KiB
Forth
# parse a decimal int at the commandline
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#
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# To run:
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# $ ./translate apps/parse-int.mu
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# $ ./a.elf 123
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# $ echo $?
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# 123
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fn main _args: (addr array addr array byte) -> _/ebx: int {
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# if no args, print a message and exit
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var args/esi: (addr array addr array byte) <- copy _args
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var n/ecx: int <- length args
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compare n, 1
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{
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break-if->
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print-string 0/screen, "usage: parse-int <integer>\n"
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return 1
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}
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# otherwise parse the first arg as an integer
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var in/ecx: (addr addr array byte) <- index args, 1
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var out/eax: int <- parse-int *in
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return out
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}
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fn parse-int _in: (addr array byte) -> _/eax: int {
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var in/esi: (addr array byte) <- copy _in
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var len/edx: int <- length in
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var i/ecx: int <- copy 0
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var result/edi: int <- copy 0
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{
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compare i, len
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break-if->=
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# result *= 10
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var ten/eax: int <- copy 0xa
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result <- multiply ten
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# c = in[i]
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var tmp/ebx: (addr byte) <- index in, i
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var c/eax: byte <- copy-byte *tmp
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#
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var g/eax: code-point-utf8 <- copy c
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var digit/eax: int <- to-decimal-digit g
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result <- add digit
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i <- increment
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loop
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}
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return result
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}
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