// Copyright 2019 The Marl Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#if defined(__x86_64__)

#include "osfiber_asm_x64.h"

#include "marl/export.h"

//You can find an explanation of this code here: https://github.com/google/marl/issues/199

MARL_EXPORT
void marl_fiber_trampoline(void (*target)(void*), void* arg) {
  target(arg);
}

MARL_EXPORT
void marl_fiber_set_target(struct marl_fiber_context* ctx,
                           void* stack,
                           uint32_t stack_size,
                           void (*target)(void*),
                           void* arg) {
  uintptr_t* stack_top = (uintptr_t*)((uint8_t*)(stack) + stack_size);
  ctx->RIP = (uintptr_t)&marl_fiber_trampoline;
  ctx->RDI = (uintptr_t)target;
  ctx->RSI = (uintptr_t)arg;
  ctx->RSP = (uintptr_t)&stack_top[-3];
  stack_top[-2] = 0;  // No return target.
}

#endif  // defined(__x86_64__)