/* Copyright (c) 2011-2021, Scott Tsai
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
#ifndef DEBUG_BREAK_H
#define DEBUG_BREAK_H

#ifdef _MSC_VER

#    define debug_break __debugbreak

#else

#    ifdef __cplusplus
extern "C" {
#    endif

#    define DEBUG_BREAK_USE_TRAP_INSTRUCTION 1
#    define DEBUG_BREAK_USE_BULTIN_TRAP 2
#    define DEBUG_BREAK_USE_SIGTRAP 3

#    if defined( __i386__ ) || defined( __x86_64__ )
#        define DEBUG_BREAK_IMPL DEBUG_BREAK_USE_TRAP_INSTRUCTION
__inline__ static void trap_instruction( void )
{
    __asm__ volatile( "int $0x03" );
}
#    elif defined( __thumb__ )
#        define DEBUG_BREAK_IMPL DEBUG_BREAK_USE_TRAP_INSTRUCTION
/* FIXME: handle __THUMB_INTERWORK__ */
__attribute__( ( always_inline ) ) __inline__ static void trap_instruction( void )
{
    /* See 'arm-linux-tdep.c' in GDB source.
     * Both instruction sequences below work. */
#        if 1
    /* 'eabi_linux_thumb_le_breakpoint' */
    __asm__ volatile( ".inst 0xde01" );
#        else
    /* 'eabi_linux_thumb2_le_breakpoint' */
    __asm__ volatile( ".inst.w 0xf7f0a000" );
#        endif

    /* Known problem:
     * After a breakpoint hit, can't 'stepi', 'step', or 'continue' in GDB.
     * 'step' would keep getting stuck on the same instruction.
     *
     * Workaround: use the new GDB commands 'debugbreak-step' and
     * 'debugbreak-continue' that become available
     * after you source the script from GDB:
     *
     * $ gdb -x debugbreak-gdb.py <... USUAL ARGUMENTS ...>
     *
     * 'debugbreak-step' would jump over the breakpoint instruction with
     * roughly equivalent of:
     * (gdb) set $instruction_len = 2
     * (gdb) tbreak *($pc + $instruction_len)
     * (gdb) jump   *($pc + $instruction_len)
     */
}
#    elif defined( __arm__ ) && !defined( __thumb__ )
#        define DEBUG_BREAK_IMPL DEBUG_BREAK_USE_TRAP_INSTRUCTION
__attribute__( ( always_inline ) ) __inline__ static void trap_instruction( void )
{
    /* See 'arm-linux-tdep.c' in GDB source,
     * 'eabi_linux_arm_le_breakpoint' */
    __asm__ volatile( ".inst 0xe7f001f0" );
    /* Known problem:
     * Same problem and workaround as Thumb mode */
}
#    elif defined( __aarch64__ ) && defined( __APPLE__ )
#        define DEBUG_BREAK_IMPL DEBUG_BREAK_USE_BULTIN_DEBUGTRAP
#    elif defined( __aarch64__ )
#        define DEBUG_BREAK_IMPL DEBUG_BREAK_USE_TRAP_INSTRUCTION
__attribute__( ( always_inline ) ) __inline__ static void trap_instruction( void )
{
    /* See 'aarch64-tdep.c' in GDB source,
     * 'aarch64_default_breakpoint' */
    __asm__ volatile( ".inst 0xd4200000" );
}
#    elif defined( __powerpc__ )
/* PPC 32 or 64-bit, big or little endian */
#        define DEBUG_BREAK_IMPL DEBUG_BREAK_USE_TRAP_INSTRUCTION
__attribute__( ( always_inline ) ) __inline__ static void trap_instruction( void )
{
    /* See 'rs6000-tdep.c' in GDB source,
     * 'rs6000_breakpoint' */
    __asm__ volatile( ".4byte 0x7d821008" );

    /* Known problem:
     * After a breakpoint hit, can't 'stepi', 'step', or 'continue' in GDB.
     * 'step' stuck on the same instruction ("twge r2,r2").
     *
     * The workaround is the same as ARM Thumb mode: use debugbreak-gdb.py
     * or manually jump over the instruction. */
}
#    elif defined( __riscv )
/* RISC-V 32 or 64-bit, whether the "C" extension
 * for compressed, 16-bit instructions are supported or not */
#        define DEBUG_BREAK_IMPL DEBUG_BREAK_USE_TRAP_INSTRUCTION
__attribute__( ( always_inline ) ) __inline__ static void trap_instruction( void )
{
    /* See 'riscv-tdep.c' in GDB source,
     * 'riscv_sw_breakpoint_from_kind' */
    __asm__ volatile( ".4byte 0x00100073" );
}
#    else
#        define DEBUG_BREAK_IMPL DEBUG_BREAK_USE_SIGTRAP
#    endif

#    ifndef DEBUG_BREAK_IMPL
#        error "debugbreak.h is not supported on this target"
#    elif DEBUG_BREAK_IMPL == DEBUG_BREAK_USE_TRAP_INSTRUCTION
__attribute__( ( always_inline ) ) __inline__ static void debug_break( void )
{
    trap_instruction();
}
#    elif DEBUG_BREAK_IMPL == DEBUG_BREAK_USE_BULTIN_DEBUGTRAP
__attribute__( ( always_inline ) ) __inline__ static void debug_break( void )
{
    __builtin_debugtrap();
}
#    elif DEBUG_BREAK_IMPL == DEBUG_BREAK_USE_BULTIN_TRAP
__attribute__( ( always_inline ) ) __inline__ static void debug_break( void )
{
    __builtin_trap();
}
#    elif DEBUG_BREAK_IMPL == DEBUG_BREAK_USE_SIGTRAP
#        include <signal.h>
__attribute__( ( always_inline ) ) __inline__ static void debug_break( void )
{
    raise( SIGTRAP );
}
#    else
#        error "invalid DEBUG_BREAK_IMPL value"
#    endif

#    ifdef __cplusplus
}
#    endif

#endif /* ifdef _MSC_VER */

#endif /* ifndef DEBUG_BREAK_H */
