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Add: semi-working printf implementation

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xamidev
2024-05-26 15:43:30 +02:00
parent 61dec7fe14
commit bb775dfa5b
9 changed files with 250 additions and 2 deletions
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189
stdio.c
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@@ -1,6 +1,7 @@
#include "io.h"
#include "stdio.h"
#include "string.h"
#include "stdint.h"
char* fb = (char *) 0x000B8000;
const unsigned VGA_WIDTH = 80;
@@ -110,3 +111,191 @@ void puts(const char* str)
}
}
void printf(const char* fmt, ...)
{
int* argp = (int*) &fmt;
int state = PRINTF_STATE_START;
int length = PRINTF_LENGTH_START;
int radix = 10;
bool sign = false;
argp++;
while (*fmt)
{
switch(state) {
case PRINTF_STATE_START:
if (*fmt == '%')
{
state = PRINTF_STATE_LENGTH;
}
else {
putc(*fmt);
}
break;
case PRINTF_STATE_LENGTH:
if (*fmt == 'h')
{
length = PRINTF_LENGTH_SHORT;
state = PRINTF_STATE_SHORT;
}
else if (*fmt == 'l')
{
length = PRINTF_LENGTH_LONG;
state = PRINTF_STATE_LONG;
}
else {
goto PRINTF_STATE_SPEC_;
}
break;
case PRINTF_STATE_SHORT:
if (*fmt == 'h')
{
length = PRINTF_LENGTH_SHORT_SHORT;
state = PRINTF_STATE_SPEC;
}
else {
goto PRINTF_STATE_SPEC_;
}
break;
case PRINTF_STATE_LONG:
if (*fmt == 'l')
{
length = PRINTF_LENGTH_LONG_LONG;
state = PRINTF_STATE_SPEC;
}
else {
goto PRINTF_STATE_SPEC_;
}
break;
case PRINTF_STATE_SPEC:
PRINTF_STATE_SPEC_:
switch(*fmt)
{
case 'c':
putc((char)*argp);
argp++;
break;
case 's':
puts(*(const char **)argp);
argp++;
break;
case '%':
putc('%');
break;
case 'd':
case 'i':
radix = 10;
sign = true;
argp = printf_number(argp, length, sign, radix);
break;
case 'u':
radix = 10;
sign = false;
argp = printf_number(argp, length, sign, radix);
break;
case 'X':
case 'x':
case 'p':
radix = 16;
sign = false;
argp = printf_number(argp, length, sign, radix);
break;
case 'o':
radix = 8;
sign = false;
argp = printf_number(argp, length, sign, radix);
break;
default:
break;
}
state = PRINTF_STATE_START;
length = PRINTF_LENGTH_START;
radix = 10;
sign = false;
break;
}
fmt++;
}
}
const char charset[] = "0123456789abcdef";
int* printf_number(int* argp, int length, bool sign, int radix)
{
char buffer[32];
unsigned long long number;
int number_sign = 1;
int pos = 0;
switch(length)
{
case PRINTF_LENGTH_SHORT_SHORT:
case PRINTF_LENGTH_SHORT:
case PRINTF_LENGTH_START:
if (sign)
{
int n = *argp;
if (n < 0)
{
n = -n;
number_sign = -1;
}
number = (unsigned long long) n;
}
else {
number = *(unsigned int*) argp;
}
argp++;
break;
case PRINTF_LENGTH_LONG:
if (sign)
{
long int n = *(long int*)argp;
if (n < 0)
{
n = -n;
number_sign = -1;
}
number = (unsigned long long) n;
}
else {
number = *(unsigned long int*) argp;
}
argp += 2;
break;
case PRINTF_LENGTH_LONG_LONG:
if (sign)
{
long long int n = *(long long int*)argp;
if (n < 0)
{
n = -n;
number_sign = -1;
}
number = (unsigned long long) n;
}
else {
number = *(unsigned long long int*) argp;
}
argp += 4;
break;
}
do {
uint32_t rem;
x86_div64_32(number, radix, &number, &rem);
buffer[pos++] = charset[rem];
} while (number > 0);
if (sign && number_sign < 0)
{
buffer[pos++] = '-';
}
while (--pos >= 0)
{
putc(buffer[pos]);
}
return argp;
}