73 lines
1.4 KiB
Text
73 lines
1.4 KiB
Text
implement Rot13;
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include "sys.m"; sys: Sys;
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include "draw.m";
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Rot13: module
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{
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init: fn(ctxt: ref Draw->Context, argv: list of string);
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};
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stdout: ref Sys->FD;
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tab: array of int;
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init(nil: ref Draw->Context, args: list of string)
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{
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sys = load Sys Sys->PATH;
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stdout = sys->fildes(1);
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inittab();
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args = tl args;
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if(args == nil)
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args = "-" :: nil;
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for(; args != nil; args = tl args){
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file := hd args;
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if(file != "-"){
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fd := sys->open(file, Sys->OREAD);
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if(fd == nil){
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sys->fprint(sys->fildes(2), "rot13: cannot open %s: %r\n", file);
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raise "fail:bad open";
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}
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rot13cat(fd, file);
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}else
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rot13cat(sys->fildes(0), "<stdin>");
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}
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}
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inittab()
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{
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tab = array[256] of int;
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for(i := 0; i < 256; i++)
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tab[i] = i;
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for(i = 'a'; i <= 'z'; i++)
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tab[i] = (((i - 'a') + 13) % 26) + 'a';
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for(i = 'A'; i <= 'Z'; i++)
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tab[i] = (((i - 'A') + 13) % 26) + 'A';
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}
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rot13(s: string): string
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{
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for(i := 0; i < len s; i++) {
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if(s[i] < 256)
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s[i] = tab[s[i]];
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}
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return s;
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}
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rot13cat(fd: ref Sys->FD, file: string)
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{
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buf := array[Sys->ATOMICIO] of byte;
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while((n := sys->read(fd, buf, len buf)) > 0) {
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obuf := array of byte (rot13(string buf));
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if(sys->write(stdout, obuf, n) < n) {
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sys->fprint(sys->fildes(2), "rot13: write error: %r\n");
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raise "fail:write error";
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}
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}
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if(n < 0) {
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sys->fprint(sys->fildes(2), "rot13: error reading %s: %r\n", file);
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raise "fail:read error";
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}
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}
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