GameBoy BGB Debug Macros (SDCC)

bgb_debug.h

// BGB Debug -- Help debugging GameBoy programs in BGB
// Copyright (c) 2019 Fabien LOISON <https://flozz.fr/>

// ==== LICENSE ==============================================================

//        DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE 
//                    Version 2, December 2004 
//
// Copyright (C) 2004 Sam Hocevar <sam@hocevar.net> 
//
// Everyone is permitted to copy and distribute verbatim or modified 
// copies of this license document, and changing it is allowed as long 
// as the name is changed. 
//
//            DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE 
//   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION 
//
//  0. You just DO WHAT THE FUCK YOU WANT TO.

// ==== USAGE ================================================================

// This file defines macros to help debugging a GameBoy program in the BGB
// emulator:
//
// Log a message in the BGB console:
//
//     BGB_LOG("your_message");
//
// Define a source code breakpoint:
//
//     BGB_BREAK;
//
// Your program must be compiled with SDCC using the -DDEBUG flag to allow the
// macros to work, else nothing will happen :)


#ifdef DEBUG


#define CONCAT_(A, B, C) A ## B ## C
#define CONCAT(A, B, C) CONCAT_(A, B, C)

#define LOG_UNIQUE_LABEL CONCAT(42424200, __COUNTER__, $)

// Log a message to the BGB console
#define BGB_LOG_(LABEL, MESSAGE)  \
__asm                 \
    .db 0x52          \
    jr LABEL          \
    .dw 0x6464        \
    .dw 0x0000        \
    .str MESSAGE      \
    LABEL:            \
__endasm;
#define BGB_LOG(MESSAGE) BGB_LOG_(LOG_UNIQUE_LABEL, MESSAGE)

// Break in the BGB debugger
#define BGB_BREAK     \
__asm                 \
    .db 0x40          \
__endasm;


#else


#define BGB_LOG(MESSAGE)
#define BGB_BREAK


#endif

example.c

#include "./bgb_debug.h"

void main(void) {
    BGB_LOG("Hello World");
    BGB_BREAK;
}