如何触发创建保存文件

How to trigger creation of savefile

我正在尝试创建一个 libretro 核心。这将是一款独立游戏,因此我将 RETRO_ENVIRONMENT_SET_SUPPORT_NO_GAME 设置为 truedocumentation 表明 retro_get_memory_* 可用于保存数据而无需显式查询 RETRO_ENVIRONMENT_GET_SAVE_DIRECTORY:

The save directory should be used to store SRAM, memory cards, high scores, etc, if the libretro core cannot use the regular memory interface (retro_get_memory_data()).

核心应该如何触发使用该接口保存数据?还是我误解了文档?

我希望前端调用 retro_get_memory_{data,size},在停止核心时从暴露的缓冲区中读取数据,将数据保存到磁盘,并在下次核心启动时将其写回暴露的缓冲区。相反,我观察到:


注意这个问题是关于save files(自动持久化数据,通常是捕捉玩家的进度),而不是save states(快照由用户触发的游戏状态)由 *serialize* 方法实现。


这是一个重现问题的简单示例(基于 this sample):

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "libretro.h"

static unsigned char c = 0;

void* retro_get_memory_data(unsigned id) {
  fprintf(stderr, "retro_get_memory_data(%d)\n", id);
  return (id == RETRO_MEMORY_SAVE_RAM) ? &c : NULL;
}

size_t retro_get_memory_size(unsigned id) {
  fprintf(stderr, "retro_get_memory_size(%d)\n", id);
  return (id == RETRO_MEMORY_SAVE_RAM) ? 1 : 0;
}

#define WIDTH 320
#define HEIGHT 240

static uint32_t* frame_buf;

void retro_init(void) { frame_buf = calloc(WIDTH * HEIGHT, sizeof(uint32_t)); }

void retro_deinit(void) {
  free(frame_buf);
  frame_buf = NULL;
}

unsigned retro_api_version(void) { return RETRO_API_VERSION; }

void retro_get_system_info(struct retro_system_info* info) {
  memset(info, 0, sizeof(*info));
  info->library_name = "SaveTest";
  info->library_version = "v1";
  info->need_fullpath = false;
  info->valid_extensions = NULL;  // Anything is fine, we don't care.
}

static retro_video_refresh_t video_cb;
static retro_environment_t environ_cb;
static retro_input_poll_t input_poll_cb;
static retro_input_state_t input_state_cb;

void retro_set_input_poll(retro_input_poll_t cb) { input_poll_cb = cb; }
void retro_set_input_state(retro_input_state_t cb) { input_state_cb = cb; }
void retro_set_video_refresh(retro_video_refresh_t cb) { video_cb = cb; }
void retro_set_environment(retro_environment_t cb) {
  environ_cb = cb;
  bool no_content = true;
  cb(RETRO_ENVIRONMENT_SET_SUPPORT_NO_GAME, &no_content);
}

void retro_get_system_av_info(struct retro_system_av_info* info) {
  float aspect = (float)WIDTH / HEIGHT;

  info->timing = (struct retro_system_timing){
      .fps = 60.0,
      .sample_rate = 0.0,
  };

  info->geometry = (struct retro_game_geometry){
      .base_width = WIDTH,
      .base_height = HEIGHT,
      .max_width = WIDTH,
      .max_height = HEIGHT,
      .aspect_ratio = aspect,
  };
}

unsigned retro_get_region(void) { return RETRO_REGION_NTSC; }

bool retro_load_game(const struct retro_game_info* info) {
  enum retro_pixel_format fmt = RETRO_PIXEL_FORMAT_XRGB8888;
  if (!environ_cb(RETRO_ENVIRONMENT_SET_PIXEL_FORMAT, &fmt)) {
    fprintf(stderr, "XRGB8888 is not supported.\n");
    return false;
  }
  (void)info;
  return true;
}

bool button(unsigned id) {
  return input_state_cb(0, RETRO_DEVICE_JOYPAD, 0, id);
}

void retro_run(void) {
  input_poll_cb();
  if (button(RETRO_DEVICE_ID_JOYPAD_LEFT) && c > 0) --c;
  if (button(RETRO_DEVICE_ID_JOYPAD_RIGHT) && c < 255) ++c;
  uint32_t color = (255 - c) | (c << 8);
  uint32_t* buf = frame_buf;
  for (unsigned i = WIDTH * HEIGHT; i > 0; --i) {
    *buf = color;
    ++buf;
  }
  video_cb(frame_buf, WIDTH, HEIGHT, WIDTH * sizeof(uint32_t));
}

void retro_unload_game(void) {}

size_t retro_serialize_size(void) { return 1; }
bool retro_serialize(void* data, size_t size) {
  fprintf(stderr, "serialize(%p, %lu) <= %u\n", data, size, c);
  *(char*)data = c;
  return true;
}
bool retro_unserialize(const void* data, size_t size) {
  c = *(char*)data;
  fprintf(stderr, "unserialize(%p, %lu) => %u\n", data, size, c);
  return true;
}

void retro_set_controller_port_device(unsigned port, unsigned device) {}
void retro_set_audio_sample(retro_audio_sample_t cb) {}
void retro_set_audio_sample_batch(retro_audio_sample_batch_t cb) {}
void retro_reset(void) {}
bool retro_load_game_special(unsigned type, const struct retro_game_info* info,
                             size_t num) {
  return false;
}
void retro_cheat_reset(void) {}
void retro_cheat_set(unsigned index, bool enabled, const char* code) {}

未记录但旨在自动保存不会触发无内容的核心。

此外,对于有内容但不支持任何内容的核心,不会触发自动保存。这是无意的,最近已修复。

参考:https://github.com/libretro/RetroArch/issues/9300