ciabatta/code/printf.h

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// NOTE: this file doesn't exist in a vacuum, it's a template for generating
// the formatted print, you should define FMT_CHAR_TYPE before including it
inline static int FMT_FUNC_NAME (void *ctx, OutputFunc out, const FMT_CHAR_TYPE *fmt, va_list args) {
size_t full_length = 0;
while (*fmt) {
// skip any normal non percent text
const FMT_CHAR_TYPE *start = fmt;
while (*fmt && *fmt != '%') fmt++;
// print all those non percent text
out(ctx, fmt - start, start);
full_length += (fmt - start);
// null terminated
if (*fmt == '\0') break;
fmt += 1;
if (*fmt == '%') {
out(ctx, 1, "%");
fmt++;
continue;
}
unsigned int precision = 0;
if (*fmt == '.') {
// custom precision
fmt++;
if (isdigit(*fmt)) {
// just a small atoi
// TODO: handle overflow, just in case(?)
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while (isdigit(*fmt)) {
precision *= 10u;
precision += (*fmt - '0');
fmt++;
}
} else if (*fmt == '*') {
int p = va_arg(args, int);
precision = p >= 0 ? ((unsigned int)p) : 0;
fmt++;
}
}
// integer length specifiers
enum {
CHAR,
SHORT,
INT,
LONG,
LLONG
} int_length = INT;
if (*fmt == 'l') {
fmt++;
if (*fmt == 'l') {
int_length = LLONG;
fmt++;
} else {
int_length = LONG;
}
} else if (*fmt == 'h') {
fmt++;
if (*fmt == 'h') {
int_length = CHAR;
fmt++;
} else {
int_length = SHORT;
}
}
FMT_CHAR_TYPE ch = *fmt++;
switch (ch) {
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case 'c': {
const char chr = va_arg(args, int);
out(ctx, 1, &chr);
full_length ++;
break;
}
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case 's': {
const FMT_CHAR_TYPE *str = va_arg(args, FMT_CHAR_TYPE*);
size_t len = FMT_STRLEN_S(str, precision ? precision : SIZE_MAX);
out(ctx, len, str);
full_length += len;
break;
}
case 'b':
case 'o':
case 'i':
case 'u':
case 'd':
case 'x':
case 'X': {
int base = 10;
switch (ch) {
case 'X': case 'x': base = 16; break;
case 'o': base = 8; break;
case 'b': base = 2; break;
default: base = 10; break;
}
const char* characters = "0123456789abcdef";
if (ch == 'X') characters = "0123456789ABCDEF";
uintmax_t i;
if (ch == 'd' || ch == 'i') {
intmax_t num = 0;
switch (int_length) {
case CHAR: num = (char) va_arg(args, int); break;
case SHORT: num = (short) va_arg(args, int); break;
case INT: num = va_arg(args, int); break;
case LONG: num = va_arg(args, long); break;
case LLONG: num = va_arg(args, long long); break;
default: break;
}
if (num < 0) {
out(ctx, 1, "-");
i = -num;
full_length += 1;
} else {
i = num;
}
} else {
switch (int_length) {
case CHAR: i = (char) va_arg(args, int); break;
case SHORT: i = (short) va_arg(args, int); break;
case INT: i = va_arg(args, int); break;
case LONG: i = va_arg(args, long); break;
case LLONG: i = va_arg(args, long long); break;
default: i = 0; break;
}
}
if (i == 0) {
out(ctx, 1, "0");
full_length += 1;
} else {
FMT_CHAR_TYPE buffer[20];
size_t len = sizeof(buffer);
// we build the number in reverse
while (i != 0) {
buffer[--len] = characters[i % base];
i /= base;
}
out(ctx, sizeof(buffer) - (len * sizeof(FMT_CHAR_TYPE)), buffer + len);
full_length += (sizeof(buffer) - len);
}
break;
}
default: break;
}
}
return full_length;
}