basic implementation of printf

[WEREMSOFT]

For people like me that gravitates towards C, it will be nice to have a printf implementation (not fully functional, but with a few cases to make it useful to print-debug or probe the kernel tables).

can be under the folder "utils" and written on the shoulders of b_output, I'm using this poor man printf, that we can use as a starting point:

printf.h

#ifndef _PRINTF_H
#define _PRINTF_H

int printf(const char* format, ...);

#endif

printf.c

#include "libBareMetal.h"
#include <stdarg.h>
#include <stddef.h>

void long_to_str(long num, char* str) {
    int i = 0;
    int is_negative = 0;

    if (num < 0) {
        is_negative = 1;
        num = -num;
    }

    do {
        str[i++] = (num % 10) + '0';
        num /= 10;
    } while (num > 0);

    if (is_negative) {
        str[i++] = '-';
    }

    str[i] = '\0';

    for (int j = 0; j < i / 2; j++) {
        char temp = str[j];
        str[j] = str[i - j - 1];
        str[i - j - 1] = temp;
    }
}

void int_to_str(int num, char* str) {
    int i = 0;
    int is_negative = 0;

    if (num < 0) {
        is_negative = 1;
        num = -num;
    }

    do {
        str[i++] = (num % 10) + '0';
        num /= 10;
    } while (num > 0);

    if (is_negative) {
        str[i++] = '-';
    }

    str[i] = '\0';

    for (int j = 0; j < i / 2; j++) {
        char temp = str[j];
        str[j] = str[i - j - 1];
        str[i - j - 1] = temp;
    }
}

int printf(const char* format, ...) {
    char buffer[1024];
    char* str = buffer;
    const char* p;
    va_list args;

    va_start(args, format);

    for (p = format; *p != '\0'; p++) {
        if (*p == '%' && (*(p + 1) == 's' || *(p + 1) == 'd' || *(p + 1) == 'l')) {
            p++;
            if (*p == 's') {
                const char* s = va_arg(args, const char*);
                while (*s) {
                    *str++ = *s++;
                }
            } else if (*p == 'd') {
                int d = va_arg(args, int);
                char num_str[32];
                int_to_str(d, num_str);
                char* ns = num_str;
                while (*ns) {
                    *str++ = *ns++;
                }
            } else if (*p == 'l' && *(p + 1) == 'd') {
                p++;
                long ld = va_arg(args, long);
                char num_str[32];
                long_to_str(ld, num_str);
                char* ns = num_str;
                while (*ns) {
                    *str++ = *ns++;
                }
            }
        } else {
            *str++ = *p;
        }
    }

    *str = '\0';
    va_end(args);

    b_output(buffer, str - buffer);
    return str - buffer;
}

I'm using it like this:

	// Gather video memory address, x & y resolution, and BPP
	frame_buffer = (unsigned char *)(*(uint64_t *)(0x5080));
	x_res = *(uint16_t *)(0x5088);
	y_res = *(uint16_t *)(0x508A);
	depth = 32;
	uint64_t frameBufferSize = x_res * y_res * 4;
	printf("\nframebuffer size %ld\n", frameBufferSize);

with the follwing result

we can reimplement the sysinfo.app the following way

#include <stdint.h>
#include "printf.h"

int main(void)
{
	unsigned char *frame_buffer;
	uint16_t x_res, y_res, cpu_speed, cores_active, cores_detected;
	uint32_t ram_amount;
	uint8_t depth;

	// Gather video memory address, x & y resolution, and BPP
	frame_buffer = (unsigned char *)(*(uint64_t *)(0x5080));
	x_res = *(uint16_t *)(0x5088);
	y_res = *(uint16_t *)(0x508A);
	depth = 32;
	uint64_t frameBufferSize = x_res * y_res * 4;

	cpu_speed = *(uint16_t *)(0x5010);
	cores_detected = *(uint16_t *)(0x5014);
	cores_active = *(uint16_t *)(0x5012);

	ram_amount = *(uint32_t *)(0x5020);

	
	printf("\nx size %d\n", x_res);
	printf("y size %d\n", y_res);
	printf("framebuffer size %ld\n", frameBufferSize);
	printf("\ncpu speed %d\n", cpu_speed);
	printf("cores dettected %d\n", cores_detected);
	printf("cores active %d\n", cores_active);
	printf("ram amount %d\n", ram_amount);


}

what gives this result

[IanSeyler]

It may be useful for get newlib (or some other C library) ported to BareMetal again.

https://github.com/ReturnInfinity/BareMetal-newlib

I had newlib running before but last I checked it wouldn't compile. Ideally we would use the latest version.