panic.c File Reference

Diagnostic and emergency error handling routines. More...

#include "error/error_strings.h"
#include <stdint.h>

Include dependency graph for panic.c:

Functions
void	print_uart0 (const char *str)
	Transmits a null-terminated string over UART0.
void	print_hex_digit (uint8_t digit)
	Converts a 4-bit nibble to a hex character and prints it.
void	print_hex (uint64_t val)
	Prints a 64-bit unsigned integer in hexadecimal format.
void	panic_print_c (long code)
	Primary C-level panic entry point.

Variables
volatile unsigned int *const	uart0_dr = (unsigned int *)0x09000000
	UART0 Data Register (MMIO).

Detailed Description

Diagnostic and emergency error handling routines.

Provides low-level UART output and panic handling routines used when the kernel encounters unrecoverable failures.

Author

Abhin Parekadan Jose

Date

2026-04-11

Function Documentation

panic_print_c()

void panic_print_c

(

long

code

)

Primary C-level panic entry point.

This function is typically called by the assembly panic_print macro. It outputs the numeric error code, resolves the human-readable error string, and indicates system halt.

Parameters

code	The numeric error code representing the failure type.

See also

error_to_string

print_hex()

void print_hex

(

uint64_t

val

)

Prints a 64-bit unsigned integer in hexadecimal format.

Iterates through the 64-bit value 4 bits at a time from most significant bit to least significant bit.

Parameters

val	The 64-bit value to be printed.

print_hex_digit()

void print_hex_digit

(

uint8_t

digit

)

Converts a 4-bit nibble to a hex character and prints it.

Parameters

digit

The digit to print (0-15).

Note

This function uses a compound literal to pass a temporary string to the UART driver.

print_uart0()

void print_uart0

(

const char *

str

)

Transmits a null-terminated string over UART0.

This function performs a simple polling-based write. It does not check for FIFO status (TX Full), assuming the baud rate/buffer is sufficient for early boot strings.

Parameters

str	A pointer to the null-terminated ASCII string to be printed.

Variable Documentation

uart0_dr

volatile unsigned int* const uart0_dr = (unsigned int *)0x09000000

UART0 Data Register (MMIO).

This pointer accesses the hardware's transmit/receive buffer. It is marked 'volatile' to prevent the compiler from optimizing out repeated writes to the same memory location, which are necessary for hardware communication.