124 lines
3.8 KiB
C
124 lines
3.8 KiB
C
/* This file is included into vb.c and cannot be compiled on its own. */
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#ifdef VBAPI
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/***************************** Utility Functions *****************************/
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/* Read a data unit from a memory buffer */
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static int32_t busReadMemory(uint8_t *mem, int type) {
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/* Little-endian implementation */
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#ifdef VB_LITTLEENDIAN
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switch (type) {
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case VB_S8 : return *(int8_t *)mem;
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case VB_U8 : return * mem;
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case VB_S16: return *(int16_t *)mem;
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case VB_U16: return *(uint16_t *)mem;
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}
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return *(int32_t *)mem;
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/* Generic implementation */
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#else
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switch (type) {
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case VB_S8 : return (int8_t) *mem;
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case VB_U8 : return *mem;
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case VB_S16: return (int16_t ) (int8_t) mem[1] << 8 | mem[0];
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case VB_U16: return (uint16_t) mem[1] << 8 | mem[0];
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}
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return (int32_t ) mem[3] << 24 | (uint32_t) mem[2] << 16 |
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(uint32_t) mem[1] << 8 | mem[0];
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#endif
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}
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/* Write a data unit to a memory buffer */
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static void busWriteMemory(uint8_t *mem, int type, int32_t value) {
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/* Little-endian implementation */
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#ifdef VB_LITTLEENDIAN
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switch (type) {
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case VB_S16: case VB_U16: *(uint16_t *)mem = value; return;
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case VB_S8 : case VB_U8 : * mem = value; return;
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}
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*(int32_t *)mem = value;
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/* Generic implementation */
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#else
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switch (type) {
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case VB_S32:
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mem[3] = value >> 24;
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mem[2] = value >> 16;
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/* Fallthrough */
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case VB_S16:
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case VB_U16:
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mem[1] = value >> 8;
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}
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mem[0] = value;
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#endif
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}
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/***************************** Module Functions ******************************/
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/* Read a data unit from the bus */
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static int32_t busRead(VB *emu, uint32_t address, int type, int debug) {
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/* Force address alignment */
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address &= ~((uint32_t) TYPE_SIZES[type] - 1);
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/* Process by address range */
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switch (address >> 24 & 7) {
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case 0 : return 0; /* VIP */
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case 1 : debug = debug; return 0; /* VSU */
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case 2 : return 0; /* Miscellaneous hardware */
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case 3 : return 0; /* Unmapped */
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case 4 : return 0; /* Game pak expansion */
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case 5 : return /* WRAM */
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busReadMemory(&emu->wram[address & 0xFFFF], type);
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case 6 : return emu->cart.sram == NULL ? 0 : /* Game pak RAM */
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busReadMemory(&emu->cart.sram
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[address & (emu->cart.sramSize - 1)], type);
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default: return emu->cart.rom == NULL ? 0 : /* Game pak ROM */
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busReadMemory(&emu->cart.rom
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[address & (emu->cart.romSize - 1)], type);
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}
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}
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/* Write a data unit to the bus */
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static void busWrite(
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VB *emu, uint32_t address, int type, uint32_t value, int debug) {
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/* Force address alignment */
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address &= ~((uint32_t) TYPE_SIZES[type] - 1);
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/* Process by address range */
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switch (address >> 24 ^ 7) {
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case 0 : return; /* VIP */
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case 1 : return; /* VSU */
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case 2 : return; /* Miscellaneous hardware */
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case 3 : return; /* Unmapped */
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case 4 : return; /* Game pak expansion */
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case 5 : /* WRAM */
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busWriteMemory(&emu->wram[address & 0xFFFF], type, value);
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return;
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case 6 : /* Cartridge RAM */
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if (emu->cart.sram != NULL)
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busWriteMemory(&emu->cart.sram
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[address & (emu->cart.sramSize - 1)], type, value);
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return;
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default: /* Cartridge ROM */
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if (debug && emu->cart.rom != NULL)
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busWriteMemory(&emu->cart.rom
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[address & (emu->cart.romSize - 1)], type, value);
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}
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}
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#endif /* VBAPI */
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