Mercurial > repos > blastem
diff segacd.c @ 1502:2564b6ba2e12 segacd
Initial skeleton of Sega CD memory handlers
author | Michael Pavone <pavone@retrodev.com> |
---|---|
date | Tue, 12 Dec 2017 09:44:33 -0800 |
parents | d51230205405 |
children | a763523dadf4 |
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--- a/segacd.c Sat Oct 21 11:51:24 2017 -0700 +++ b/segacd.c Tue Dec 12 09:44:33 2017 -0800 @@ -0,0 +1,257 @@ +#include <stdlib.h> +#include <string.h> +#include "segacd.h" +#include "genesis.h" +#include "util.h" + +static void *prog_ram_wp_write16(uint32_t address, void *vcontext, uint16_t value) +{ + return vcontext; +} + +static void *prog_ram_wp_write8(uint32_t address, void *vcontext, uint8_t value) +{ + return vcontext; +} + +static uint16_t work_ram_2M_read16(uint32_t address, void *vcontext) +{ + return 0; +} + +static uint8_t work_ram_2M_read8(uint32_t address, void *vcontext) +{ + return 0; +} + +static void *work_ram_2M_write16(uint32_t address, void *vcontext, uint16_t value) +{ + return vcontext; +} + +static void *work_ram_2M_write8(uint32_t address, void *vcontext, uint8_t value) +{ + return vcontext; +} + +static uint16_t work_ram_1M_read16(uint32_t address, void *vcontext) +{ + return 0; +} + +static uint8_t work_ram_1M_read8(uint32_t address, void *vcontext) +{ + return 0; +} + +static void *work_ram_1M_write16(uint32_t address, void *vcontext, uint16_t value) +{ + return vcontext; +} + +static void *work_ram_1M_write8(uint32_t address, void *vcontext, uint8_t value) +{ + return vcontext; +} + +static uint8_t pcm_read8(uint32_t address, void *vcontext) +{ + return 0; +} + +static uint16_t pcm_read16(uint32_t address, void *vcontext) +{ + return 0xFF00 | pcm_read8(address+1, vcontext); +} + +static void *pcm_write8(uint32_t address, void *vcontext, uint8_t value) +{ + return vcontext; +} + +static void *pcm_write16(uint32_t address, void *vcontext, uint16_t value) +{ + return pcm_write8(address+1, vcontext, value); +} + +static uint16_t sub_gate_read16(uint32_t address, void *vcontext) +{ + m68k_context *m68k = vcontext; + segacd_context *cd = m68k->system; + return cd->gate_array[(address & 0x1FF) >> 1]; +} + +static uint8_t sub_gate_read8(uint32_t address, void *vcontext) +{ + m68k_context *m68k = vcontext; + segacd_context *cd = m68k->system; + uint16_t val = cd->gate_array[(address & 0x1FF) >> 1]; + return address & 1 ? val : val >> 8; +} + +static void *sub_gate_write16(uint32_t address, void *vcontext, uint16_t value) +{ + m68k_context *m68k = vcontext; + segacd_context *cd = m68k->system; + uint32_t reg = (address & 0x1FF) >> 1; + switch (reg) + { + case 0x7: + cd->gate_array[reg] &= 0xFF00; + cd->gate_array[reg] |= value & 0xFF; + break; + case 0x10: + case 0x11: + case 0x12: + case 0x13: + case 0x14: + case 0x15: + case 0x16: + case 0x17: + //no effects for these other than saving the value + cd->gate_array[reg] = value; + break; + default: + printf("Unhandled gate array write %X:%X\n", address, value); + } + return vcontext; +} + +static void *sub_gate_write8(uint32_t address, void *vcontext, uint8_t value) +{ + m68k_context *m68k = vcontext; + segacd_context *cd = m68k->system; + uint32_t reg = (address & 0x1FF) >> 1; + uint16_t value16; + if (address & 1) { + value16 = cd->gate_array[reg] & 0xFF00 | value; + } else { + value16 = cd->gate_array[reg] & 0xFF | (value << 8); + } + return sub_gate_write16(address, vcontext, value16); +} + +static uint16_t main_gate_read16(uint32_t address, void *vcontext) +{ + m68k_context *m68k = vcontext; + segacd_context *cd = m68k->system; + return cd->gate_array[(address & 0x1FF) >> 1]; +} + +static uint8_t main_gate_read8(uint32_t address, void *vcontext) +{ + m68k_context *m68k = vcontext; + segacd_context *cd = m68k->system; + uint16_t val = cd->gate_array[(address & 0x1FF) >> 1]; + return address & 1 ? val : val >> 8; +} + +static void *main_gate_write16(uint32_t address, void *vcontext, uint16_t value) +{ + m68k_context *m68k = vcontext; + genesis_context *gen = m68k->system; + segacd_context *cd = gen->expansion; + uint32_t reg = (address & 0x1FF) >> 1; + switch (reg) + { + case 0x7: + cd->gate_array[reg] &= 0xFF; + cd->gate_array[reg] |= value & 0xFF00; + break; + case 0x8: + case 0x9: + case 0xA: + case 0xB: + case 0xC: + case 0xD: + case 0xE: + case 0xF: + //no effects for these other than saving the value + cd->gate_array[reg] = value; + break; + default: + printf("Unhandled gate array write %X:%X\n", address, value); + } + return vcontext; +} + +static void *main_gate_write8(uint32_t address, void *vcontext, uint8_t value) +{ + m68k_context *m68k = vcontext; + genesis_context *gen = m68k->system; + segacd_context *cd = gen->expansion; + uint32_t reg = (address & 0x1FF) >> 1; + uint16_t value16; + if (address & 1) { + value16 = cd->gate_array[reg] & 0xFF00 | value; + } else { + value16 = cd->gate_array[reg] & 0xFF | (value << 8); + } + return main_gate_write16(address, vcontext, value16); +} + +segacd_context *alloc_configure_segacd(system_media *media, uint32_t opts, uint8_t force_region, rom_info *info) +{ + static memmap_chunk sub_cpu_map[] = { + {0x000000, 0x00FEFF, 0x0000, .flags=MMAP_READ | MMAP_CODE, .write_16 = prog_ram_wp_write16, .write_8 = prog_ram_wp_write8}, + {0x00FF00, 0x07FFFF, 0x0000, .flags=MMAP_READ | MMAP_WRITE | MMAP_CODE}, + {0x080000, 0x0BFFFF, 0x0000, .flags=MMAP_READ | MMAP_WRITE | MMAP_CODE | MMAP_PTR_IDX | MMAP_FUNC_NULL, .ptr_index = 0, + .read_16 = work_ram_2M_read16, .write_16 = work_ram_2M_write16, .read_8 = work_ram_2M_read8, .write_8 = work_ram_2M_write8}, + {0x0C0000, 0x0DFFFF, 0x0000, .flags=MMAP_READ | MMAP_WRITE | MMAP_CODE | MMAP_PTR_IDX | MMAP_FUNC_NULL, .ptr_index = 1, + .read_16 = work_ram_1M_read16, .write_16 = work_ram_1M_write16, .read_8 = work_ram_1M_read8, .write_8 = work_ram_1M_write8}, + {0xFE0000, 0xFEFFFF, 0x3FFF, .flags=MMAP_READ | MMAP_WRITE | MMAP_ONLY_ODD}, + {0xFF0000, 0xFF7FFF, 0x0000, .read_16 = pcm_read16, .write_16 = pcm_write16, .read_8 = pcm_read8, .write_8 = pcm_write8}, + {0xFF8000, 0xFF81FF, 0x0000, .read_16 = sub_gate_read16, .write_16 = sub_gate_write16, .read_8 = sub_gate_read8, .write_8 = sub_gate_write8} + }; + segacd_context *cd = calloc(sizeof(segacd_context), 1); + FILE *f = fopen("cdbios.bin", "rb"); + if (!f) { + fatal_error("Failed to open CD firmware for reading"); + } + long firmware_size = file_size(f); + uint32_t adjusted_size = nearest_pow2(firmware_size); + cd->rom = malloc(adjusted_size); + if (firmware_size != fread(cd->rom, 1, firmware_size, f)) { + fatal_error("Failed to read CD firmware"); + } + cd->rom_mut = malloc(adjusted_size); + memcpy(cd->rom_mut, cd->rom, adjusted_size); + byteswap_rom(firmware_size, cd->rom); + cd->prog_ram = malloc(512*1024); + cd->work_ram = malloc(256*1024); + cd->pcm_ram = malloc(64*1024); + //TODO: Load state from file + cd->bram = malloc(8*1024); + + sub_cpu_map[0].buffer = sub_cpu_map[1].buffer = cd->prog_ram; + sub_cpu_map[4].buffer = cd->bram; + m68k_options *mopts = malloc(sizeof(m68k_options)); + init_m68k_opts(mopts, sub_cpu_map, sizeof(sub_cpu_map) / sizeof(*sub_cpu_map), 4); + cd->m68k = init_68k_context(mopts, NULL); + cd->m68k->system = cd; + cd->busreq = 1; + cd->busack = 1; + + return cd; +} + +memmap_chunk *segacd_main_cpu_map(segacd_context *cd, uint32_t *num_chunks) +{ + static memmap_chunk main_cpu_map[] = { + {0x000000, 0x01FFFF, 0x00000, .flags=MMAP_READ}, + {0x020000, 0x03FFFF, 0x1FFFF, .flags=MMAP_READ|MMAP_WRITE|MMAP_PTR_IDX|MMAP_FUNC_NULL, .ptr_index = 0},//TODO: support running main CPU code from here + {0x040000, 0x05FFFF, 0x1FFFF, .flags=MMAP_READ}, //first ROM alias + //TODO: additional ROM/prog RAM aliases + {0x200000, 0x01FFFF, 0x1FFFF, .flags=MMAP_READ|MMAP_WRITE|MMAP_PTR_IDX|MMAP_FUNC_NULL, .ptr_index = 1}, + {0x220000, 0x03FFFF, 0x1FFFF, .flags=MMAP_READ|MMAP_WRITE|MMAP_PTR_IDX|MMAP_FUNC_NULL, .ptr_index = 2}, + }; + //TODO: support cart boot maps + //TODO: support BRAM cart + main_cpu_map[0].buffer = cd->rom_mut; + main_cpu_map[2].buffer = cd->rom; + main_cpu_map[1].buffer = cd->prog_ram; + main_cpu_map[3].buffer = cd->work_ram; + main_cpu_map[3].buffer = cd->work_ram + 0x10000; + *num_chunks = sizeof(main_cpu_map) / sizeof(*main_cpu_map); + return main_cpu_map; +}