From 57c7c53173bbfb5a29ba41e774007bbfc880b54e Mon Sep 17 00:00:00 2001 From: Alcaro Date: Thu, 5 Jun 2014 18:57:52 +0200 Subject: [PATCH] Add memory descriptor interface to libretro.h, for use with cheats. --- libretro.h | 105 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 105 insertions(+) diff --git a/libretro.h b/libretro.h index c87eca09d2..0327ef3a19 100755 --- a/libretro.h +++ b/libretro.h @@ -635,6 +635,111 @@ enum retro_mod // The core must pass an array of const struct retro_controller_info which is terminated with // a blanked out struct. Each element of the struct corresponds to an ascending port index to retro_set_controller_port_device(). // Even if special device types are set in the libretro core, libretro should only poll input based on the base input device types. +#define RETRO_ENVIRONMENT_SET_MEMORY_MAPS (36 | RETRO_ENVIRONMENT_EXPERIMENTAL) + // const struct retro_memory_map * -- + // This environment call lets a libretro core tell the frontend about the memory maps this + // core emulates. This can be used to implement, for example, cheats in a core-agnostic way. + // + // Should only be used by emulators; it doesn't make much sense for anything else. + // It is recommended to expose all relevant pointers through retro_get_memory_* as well. + // + // Can be called from retro_init and retro_load_game. + // + +#define RETRO_MEMDESC_CONST (1 << 0) // The frontend will never change this memory area once retro_load_game has returned. +#define RETRO_MEMDESC_BIGENDIAN (1 << 1) // The memory area contains big endian data. Default is little endian. +#define RETRO_MEMDESC_ALIGN_2 (1 << 16) // All memory access in this area is aligned to their own size, or 2, whichever is smaller. +#define RETRO_MEMDESC_ALIGN_4 (2 << 16) +#define RETRO_MEMDESC_ALIGN_8 (3 << 16) +#define RETRO_MEMDESC_MINSIZE_2 (1 << 24) // All memory in this region is accessed at least 2 bytes at the time. +#define RETRO_MEMDESC_MINSIZE_4 (2 << 24) +#define RETRO_MEMDESC_MINSIZE_8 (3 << 24) +struct retro_memory_descriptor { + uint64_t flags; + + //Pointer to the start of the relevant ROM or RAM chip. + //It's strongly recommended to use 'offset' if possible, rather than doing math on the pointer. + //If the same byte is mapped my multiple descriptors, their descriptors must have the same pointer. + //If 'start' does not point to the first byte in the pointer, put the difference in 'offset' instead. + //May be NULL if there's nothing usable here (e.g. hardware registers and open bus). No flags should be set if the pointer is NULL. + //It's recommended to minimize the number of descriptors if possible, but not mandatory. + void * ptr; + size_t offset; + + //This is the location in the emulated address space where the mapping starts. + size_t start; + + //Which bits must be same as in 'start' for this mapping to apply. + //The first memory descriptor to claim a certain byte is the one that applies. + //A bit which is set in 'start' must also be set in this. + //Can be zero, in which case each byte is assumed mapped exactly once. In this case, 'len' must be a power of two. + size_t select; + + //If this is nonzero, the set bits are assumed not connected to the memory chip's address pins. + size_t disconnect; + + //This one tells the size of the current memory area. + //If, after start+disconnect are applied, the address is higher than this, the highest bit of the address is cleared. + //If the address is still too high, the next highest bit is cleared. + //Can be zero, in which case it's assumed to be infinite (as limited by 'select' and 'disconnect'). + size_t len; + + //To go from emulated address to physical address, the following order applies: + //Subtract 'start', pick off 'disconnect', apply 'len', add 'offset'. + + //The address space name must consist of only a-zA-Z0-9_-, should be as short as feasible (maximum length is 8 plus the NUL), + // and may not be any other address space plus one or more 0-9A-F at the end. + //However, multiple memory descriptors for the same address space is allowed, and the address + // space name can be empty. NULL is treated as empty. + //Address space names are case sensitive, but avoid lowercase if possible. + //The same pointer may exist in multiple address spaces. + //Examples: + // blank+blank - valid (multiple things may be mapped in the same namespace) + // 'Sp'+'Sp' - valid (multiple things may be mapped in the same namespace) + // 'A'+'B' - valid (neither is a prefix of each other) + // 'S'+blank - valid ('S' is not in 0-9A-F) + // 'a'+blank - valid ('a' is not in 0-9A-F) + // 'a'+'A' - valid (neither is a prefix of each other) + // 'AR'+blank - valid ('R' is not in 0-9A-F) + // 'ARB'+blank - valid (the B can't be part of the address either, because there is no namespace 'AR') + // blank+'B' - not valid, because it's ambigous which address space B1234 would refer to. + // The length can't be used for that purpose; the frontend may want to append arbitrary data to an address, without a separator. + const char * addrspace; +}; +//The frontend may use the largest value of 'start'+'select' in a certain namespace to infer the size of the address space. +//If the address space is larger than that, a mapping with .ptr=NULL should be at the end of the array, with .select set to all ones for as long as the address space is big. +//Sample descriptors (minus .ptr, and RETRO_MEMFLAG_ on the flags): +//SNES WRAM: +// .start=0x7E0000, .len=0x20000 +//(Note that this must be mapped before the ROM in most cases; some of the ROM mappers try to claim $7E0000, or at least $7E8000.) +//SNES SPC700 RAM: +// .addrspace="S", .len=0x10000 +//SNES WRAM mirrors: +// .flags=MIRROR, .start=0x000000, .select=0xC0E000, .len=0x2000 +// .flags=MIRROR, .start=0x800000, .select=0xC0E000, .len=0x2000 +//SNES WRAM mirrors, alternate equivalent descriptor: +// .flags=MIRROR, .select=0x40E000, .disconnect=~0x1FFF +//(Various similar constructions can be created by combining parts of the above two.) +//SNES LoROM (512KB, mirrored a couple of times): +// .flags=CONST, .start=0x008000, .select=0x408000, .disconnect=0x8000, .len=512*1024 +// .flags=CONST, .start=0x400000, .select=0x400000, .disconnect=0x8000, .len=512*1024 +//SNES HiROM (4MB): +// .flags=CONST, .start=0x400000, .select=0x400000, .len=4*1024*1024 +// .flags=CONST, .offset=0x8000, .start=0x008000, .select=0x408000, .len=4*1024*1024 +//SNES ExHiROM (8MB): +// .flags=CONST, .offset=0, .start=0xC00000, .select=0xC00000, .len=4*1024*1024 +// .flags=CONST, .offset=4*1024*1024, .start=0x400000, .select=0xC00000, .len=4*1024*1024 +// .flags=CONST, .offset=0x8000, .start=0x808000, .select=0xC08000, .len=4*1024*1024 +// .flags=CONST, .offset=4*1024*1024+0x8000, .start=0x008000, .select=0xC08000, .len=4*1024*1024 +//Clarify the size of the address space: +// .ptr=NULL, .select=0xFFFFFF +//.len can be implied by .select in many of them, but was included for clarity. + +struct retro_memory_map +{ + const struct retro_memory_descriptor * descriptors; + unsigned num_descriptors; +}; struct retro_controller_description {