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99 lines
2.2 KiB
99 lines
2.2 KiB
// See LICENSE for license details.
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#include <stdint.h>
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#include <string.h>
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#include <stdarg.h>
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#include <stdbool.h>
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int vsnprintf(char* out, size_t n, const char* s, va_list vl)
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{
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bool format = false;
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bool longarg = false;
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size_t pos = 0;
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for( ; *s; s++)
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{
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if(format)
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{
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switch(*s)
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{
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case 'l':
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longarg = true;
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break;
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case 'p':
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longarg = true;
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if (++pos < n) out[pos-1] = '0';
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if (++pos < n) out[pos-1] = 'x';
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case 'x':
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{
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long num = longarg ? va_arg(vl, long) : va_arg(vl, int);
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for(int i = 2*(longarg ? sizeof(long) : sizeof(int))-1; i >= 0; i--) {
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int d = (num >> (4*i)) & 0xF;
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if (++pos < n) out[pos-1] = (d < 10 ? '0'+d : 'a'+d-10);
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}
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longarg = false;
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format = false;
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break;
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}
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case 'd':
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{
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long num = longarg ? va_arg(vl, long) : va_arg(vl, int);
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if (num < 0) {
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num = -num;
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if (++pos < n) out[pos-1] = '-';
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}
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long digits = 1;
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for (long nn = num; nn /= 10; digits++)
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;
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for (int i = digits-1; i >= 0; i--) {
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if (pos + i + 1 < n) out[pos + i] = '0' + (num % 10);
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num /= 10;
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}
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pos += digits;
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longarg = false;
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format = false;
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break;
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}
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case 's':
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{
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const char* s2 = va_arg(vl, const char*);
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while (*s2) {
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if (++pos < n)
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out[pos-1] = *s2;
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s2++;
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}
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longarg = false;
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format = false;
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break;
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}
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case 'c':
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{
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if (++pos < n) out[pos-1] = (char)va_arg(vl,int);
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longarg = false;
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format = false;
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break;
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}
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default:
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break;
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}
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}
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else if(*s == '%')
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format = true;
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else
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if (++pos < n) out[pos-1] = *s;
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}
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if (pos < n)
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out[pos] = 0;
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else if (n)
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out[n-1] = 0;
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return pos;
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}
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int snprintf(char* out, size_t n, const char* s, ...)
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{
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va_list vl;
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va_start(vl, s);
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int res = vsnprintf(out, n, s, vl);
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va_end(vl);
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return res;
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}
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