mirror of
https://github.com/ekeeke/Genesis-Plus-GX.git
synced 2024-09-21 13:49:44 +02:00
86 lines
2.4 KiB
C
86 lines
2.4 KiB
C
/*
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basic, incomplete SSP160x (SSP1601?) interpreter
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with SVP memory controller emu
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(c) Copyright 2008, Grazvydas "notaz" Ignotas
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Free for non-commercial use.
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For commercial use, separate licencing terms must be obtained.
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Modified for Genesis Plus GX (Eke-Eke): added BIG ENDIAN support, fixed addr/code inversion
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*/
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#include "shared.h"
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svp_t *svp;
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static void svp_write_dram(uint32 address, uint32 data)
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{
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*(uint16 *)(svp->dram + (address & 0x1fffe)) = data;
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if (data)
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{
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if (address == 0x30fe06) svp->ssp1601.emu_status &= ~SSP_WAIT_30FE06;
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else if (address == 0x30fe08) svp->ssp1601.emu_status &= ~SSP_WAIT_30FE08;
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}
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}
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static uint32 svp_read_cell_1(uint32 address)
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{
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address = (address & 0xe002) | ((address & 0x7c) << 6) | ((address & 0x1f80) >> 5);
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return *(uint16 *)(svp->dram + address);
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}
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static uint32 svp_read_cell_2(uint32 address)
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{
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address = (address & 0xf002) | ((address & 0x3c) << 6) | ((address & 0xfc0) >> 4);
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return *(uint16 *)(svp->dram + address);
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}
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static uint32 svp_read_cell_byte(uint32 address)
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{
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uint16 data = m68k.memory_map[address >> 16].read16(address);
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if (address & 0x01)
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{
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return (data & 0xff);
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}
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return (data >> 8);
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}
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void svp_init(void)
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{
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svp = (void *) ((char *)cart.rom + 0x200000);
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memset(svp, 0, sizeof(*svp));
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m68k.memory_map[0x30].base = svp->dram;
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m68k.memory_map[0x30].read8 = NULL;
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m68k.memory_map[0x30].read16 = NULL;
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m68k.memory_map[0x30].write8 = NULL;
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m68k.memory_map[0x30].write16 = svp_write_dram;
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zbank_memory_map[0x30].read = NULL;
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zbank_memory_map[0x30].write = NULL;
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m68k.memory_map[0x31].base = svp->dram + 0x10000;
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m68k.memory_map[0x31].read8 = NULL;
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m68k.memory_map[0x31].read16 = NULL;
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m68k.memory_map[0x31].write8 = NULL;
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m68k.memory_map[0x31].write16 = NULL;
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zbank_memory_map[0x31].read = NULL;
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zbank_memory_map[0x31].write = NULL;
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m68k.memory_map[0x39].read8 = svp_read_cell_byte;
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m68k.memory_map[0x39].read16 = svp_read_cell_1;
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zbank_memory_map[0x39].read = svp_read_cell_byte;
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m68k.memory_map[0x3a].read8 = svp_read_cell_byte;
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m68k.memory_map[0x3a].read16 = svp_read_cell_2;
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zbank_memory_map[0x3a].read = svp_read_cell_byte;
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}
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void svp_reset(void)
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{
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memcpy(svp->iram_rom + 0x800, cart.rom + 0x800, 0x20000 - 0x800);
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ssp1601_reset(&svp->ssp1601);
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}
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