err.c

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//err.c - err handling and so on
#include "err.h"
#include "types.h"
 
//note: raw vga used incase prt was comprimised, minimal dependencys
 
/**
 * @brief panic halts the system with a kernel panic message
 *
 * panic is a function that clears the screen to red, displays a
 * kernel panic banner with the provided message, and halts forever
 * @param txt, the error message to display
 *
 * when panic is called the system becomes unrecoverable, it will
 * always halt, so use it only for fatal unrecoverable errors
 *
 * using panic is done with
 * @code{.c}
 * #include "../lib/err.h" //or just err.h
 * panic("something went wrong");
 * @endcode
 *
 * @see assert()
 */
NORETURN void __panic(const char* txt) {
    uint16_t* vga = (uint16_t*)0xB8000;
    //clear screen
    for (int i = 0; i < 2000; i++) {
        vga[i] = (uint16_t)(0x0C << 8) | ' '; //red background, space character aka empty
    }
    
    //prt KERNEL PANIC
    const char* kmsg = "KERNEL PANIC";
    int i = 0;
    while (kmsg[i] != 0) {
        vga[i] = (uint16_t)((0x0C << 8) | kmsg[i]);  //red text for error-ness
        i++;
    }
    
    //prt err on row 2
    i = 0;
    while (txt[i] != 0) {
        vga[2 * 80 + i] = (uint16_t)((0x0C << 8) | txt[i]);
        i++;
    }
    
    //prt "system halted" on row 4
    const char* hmsg = "system halted";
    i = 0;
    while (hmsg[i] != 0) {
        vga[4 * 80 + i] = (uint16_t)((0x0C << 8) | hmsg[i]);
        i++;
    }
    
    //halt forever
    while(1);
}