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#include <shared/mem.h>
#include <shared/printf.h>
int __printf_internal(const char *fmt, va_list argp,
void (*back)(void*, const char*, size_t), void *back_arg)
{
const char *seg = fmt; // beginning of the current segment
int total = 0;
for (;;) {
char c = *fmt++;
switch (c) {
case '\0':
back(back_arg, seg, fmt - seg - 1);
return total + (fmt - seg - 1);
case '%':
back(back_arg, seg, fmt - seg - 1);
total += fmt - seg - 1;
size_t pad_len = 0;
c = *fmt++;
while (1) {
switch (c) {
case '0':
pad_len = *fmt++ - '0'; // can skip over the null byte, idc
break;
default:
goto modifier_break;
}
c = *fmt++;
}
modifier_break:
switch (c) {
case 'c':
char c = va_arg(argp, int);
back(back_arg, &c, 1);
total += 1;
break;
case 's':
const char *s = va_arg(argp, char*);
if (s) {
back(back_arg, s, strlen(s));
total += strlen(s);
}
break;
case 'x':
unsigned long n = va_arg(argp, long);
size_t i = 4; // nibbles * 4
while (n >> i && i < (sizeof(n) * 8))
i += 4;
if (i < pad_len * 4)
i = pad_len * 4;
while (i > 0) {
i -= 4;
char h = '0' + ((n >> i) & 0xf);
if (h > '9') h += 'a' - '9' - 1;
back(back_arg, &h, 1);
total++;
}
break;
}
seg = fmt;
break;
}
}
}
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