94 lines
1.3 KiB
C
94 lines
1.3 KiB
C
#include <u.h>
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#include <libc.h>
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#define VLONG_MAX ~(((vlong) 1)<<63)
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#define VLONG_MIN (((vlong) 1)<<63)
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vlong
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strtoll(const char *nptr, char **endptr, int base)
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{
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char *p;
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vlong n, nn, m;
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int c, ovfl, v, neg, ndig;
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p = (char*)nptr;
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neg = 0;
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n = 0;
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ndig = 0;
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ovfl = 0;
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/*
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* White space
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*/
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for(;; p++) {
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switch(*p) {
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case ' ':
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case '\t':
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case '\n':
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case '\f':
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case '\r':
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case '\v':
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continue;
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}
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break;
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}
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/*
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* Sign
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*/
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if(*p=='-' || *p=='+')
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if(*p++ == '-')
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neg = 1;
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/*
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* Base
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*/
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if(base==0){
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base = 10;
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if(*p == '0') {
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base = 8;
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if(p[1]=='x' || p[1]=='X') {
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p += 2;
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base = 16;
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}
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}
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} else
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if(base==16 && *p=='0') {
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if(p[1]=='x' || p[1]=='X')
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p += 2;
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} else
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if(base<0 || 36<base)
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goto Return;
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/*
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* Non-empty sequence of digits
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*/
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m = VLONG_MAX/base;
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for(;; p++,ndig++) {
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c = *p;
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v = base;
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if('0'<=c && c<='9')
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v = c - '0';
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else
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if('a'<=c && c<='z')
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v = c - 'a' + 10;
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else
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if('A'<=c && c<='Z')
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v = c - 'A' + 10;
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if(v >= base)
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break;
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if(n > m)
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ovfl = 1;
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nn = n*base + v;
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if(nn < n)
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ovfl = 1;
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n = nn;
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}
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Return:
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if(ndig == 0)
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p = (char*)nptr;
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if(endptr)
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*endptr = p;
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if(ovfl){
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if(neg)
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return VLONG_MIN;
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return VLONG_MAX;
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}
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if(neg)
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return -n;
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return n;
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}
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