// SPDX-FileCopyrightText: Copyright (c) 2013-2014 Damien P. George
// SPDX-FileCopyrightText: 2014 MicroPython & CircuitPython contributors (https://github.com/adafruit/circuitpython/graphs/contributors)
//
// SPDX-License-Identifier: MIT

#include <stdio.h>

#include "py/mpstate.h"
#include "py/gc.h"

#if MICROPY_ENABLE_GC

// Even if we have specific support for an architecture, it is
// possible to force use of setjmp-based implementation.
#if !MICROPY_GCREGS_SETJMP

// We capture here callee-save registers, i.e. ones which may contain
// interesting values held there by our callers. It doesn't make sense
// to capture caller-saved registers, because they, well, put on the
// stack already by the caller.
#if defined(__x86_64__)
typedef mp_uint_t regs_t[6];

STATIC void gc_helper_get_regs(regs_t arr) {
    register long rbx asm ("rbx");
    register long rbp asm ("rbp");
    register long r12 asm ("r12");
    register long r13 asm ("r13");
    register long r14 asm ("r14");
    register long r15 asm ("r15");
#ifdef __clang__
    // TODO:
    // This is dirty workaround for Clang. It tries to get around
    // uncompliant (wrt to GCC) behavior of handling register variables.
    // Application of this patch here is random, and done only to unbreak
    // MacOS build. Better, cross-arch ways to deal with Clang issues should
    // be found.
    asm("" : "=r"(rbx));
    asm("" : "=r"(rbp));
    asm("" : "=r"(r12));
    asm("" : "=r"(r13));
    asm("" : "=r"(r14));
    asm("" : "=r"(r15));
#endif
    arr[0] = rbx;
    arr[1] = rbp;
    arr[2] = r12;
    arr[3] = r13;
    arr[4] = r14;
    arr[5] = r15;
}

#elif defined(__i386__)

typedef mp_uint_t regs_t[4];

STATIC void gc_helper_get_regs(regs_t arr) {
    register long ebx asm ("ebx");
    register long esi asm ("esi");
    register long edi asm ("edi");
    register long ebp asm ("ebp");
    arr[0] = ebx;
    arr[1] = esi;
    arr[2] = edi;
    arr[3] = ebp;
}

#elif defined(__thumb2__) || defined(__thumb__) || defined(__arm__)

typedef mp_uint_t regs_t[10];

STATIC void gc_helper_get_regs(regs_t arr) {
    register long r4 asm ("r4");
    register long r5 asm ("r5");
    register long r6 asm ("r6");
    register long r7 asm ("r7");
    register long r8 asm ("r8");
    register long r9 asm ("r9");
    register long r10 asm ("r10");
    register long r11 asm ("r11");
    register long r12 asm ("r12");
    register long r13 asm ("r13");
    arr[0] = r4;
    arr[1] = r5;
    arr[2] = r6;
    arr[3] = r7;
    arr[4] = r8;
    arr[5] = r9;
    arr[6] = r10;
    arr[7] = r11;
    arr[8] = r12;
    arr[9] = r13;
}

#else

// If we don't have architecture-specific optimized support,
// just fall back to setjmp-based implementation.
#undef MICROPY_GCREGS_SETJMP
#define MICROPY_GCREGS_SETJMP (1)

#endif // Arch-specific selection
#endif // !MICROPY_GCREGS_SETJMP

// If MICROPY_GCREGS_SETJMP was requested explicitly, or if
// we enabled it as a fallback above.
#if MICROPY_GCREGS_SETJMP
#include <setjmp.h>

typedef jmp_buf regs_t;

STATIC void gc_helper_get_regs(regs_t arr) {
    setjmp(arr);
}

#endif // MICROPY_GCREGS_SETJMP

void gc_collect(void) {
    gc_collect_start();
    regs_t regs;
    gc_helper_get_regs(regs);
    // GC stack (and regs because we captured them)
    void **regs_ptr = (void**)(void*)&regs;
    gc_collect_root(regs_ptr, ((mp_uint_t)MP_STATE_THREAD(stack_top) - (mp_uint_t)&regs) / sizeof(mp_uint_t));
    #if MICROPY_EMIT_NATIVE
    mp_unix_mark_exec();
    #endif
    gc_collect_end();
}

#endif //MICROPY_ENABLE_GC