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Advertise Jaguar memory map for RetroAchievements support #112

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Advertise Jaguar memory map for RetroAchievements support #112

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Advertise Jaguar memory map for RetroAchievements support
claude Apr 17, 2026
da67876
Update libretro.c
JoeMatt Apr 19, 2026
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19 changes: 19 additions & 0 deletions libretro.c
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Original file line number Diff line number Diff line change
Expand Up @@ -994,6 +994,25 @@ bool retro_load_game(const struct retro_game_info *info)
JaguarLoadFile((uint8_t*)info->data, info->size);
JaguarReset();

/* Advertise the Jaguar memory map to the frontend so features like
* RetroAchievements (rcheevos) can resolve emulated addresses to
* the host buffers backing them. */
{
struct retro_memory_descriptor descs[1];
struct retro_memory_map memmap;

memset(descs, 0, sizeof(descs));
descs[0].flags = RETRO_MEMDESC_SYSTEM_RAM | RETRO_MEMDESC_BIGENDIAN;
descs[0].ptr = jaguarMainRAM;
descs[0].start = 0x000000;
descs[0].len = 0x200000;
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Copilot AI Apr 17, 2026

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These are magic constants for the main RAM mapping. To reduce the chance of future mismatches, prefer using a named constant (e.g., JAGUAR_MAIN_RAM_SIZE) or sizeof (if jaguarMainRAM is a real array in this translation unit) for len.

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descs[0].addrspace = "RAM";

memmap.descriptors = descs;
memmap.num_descriptors = sizeof(descs) / sizeof(descs[0]);
environ_cb(RETRO_ENVIRONMENT_SET_MEMORY_MAPS, &memmap);
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}
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Copilot AI Apr 17, 2026

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The descs array (and memmap) are stack-allocated and go out of scope when retro_load_game returns, but frontends may keep and query the memory map later. This can leave the frontend with dangling pointers for memmap.descriptors, causing incorrect reads or crashes. Make the descriptors and the retro_memory_map storage persist for the lifetime of the loaded game (e.g., static/global storage, or heap-allocate and free on retro_unload_game).

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@JoeMatt JoeMatt Apr 19, 2026

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@copilot apply changes based on this feedback


/* The frontend will load .srm data into our save buffer (returned by
* retro_get_memory_data) after this function returns but before the
* first retro_run(). We unpack it on the first frame. */
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