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