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mgba
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Minor ROM access optimization

This commit is contained in:
Jeffrey Pfau 2013-04-09 22:20:35 -07:00
parent 027e27caa4
commit d3abd2dc63
4 changed files with 53 additions and 5 deletions
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4
src/arm.h
View File

@ -76,6 +76,10 @@ struct ARMMemory {
void (*store32)(struct ARMMemory*, uint32_t address, int32_t value);
void (*store16)(struct ARMMemory*, uint32_t address, int16_t value);
void (*store8)(struct ARMMemory*, uint32_t address, int8_t value);
uint32_t* activeRegion;
uint32_t activeMask;
void (*setActiveRegion)(struct ARMMemory*, uint32_t address);
};
struct ARMBoard {

38
src/gba.c
View File

@ -5,6 +5,8 @@
static const char* GBA_CANNOT_MMAP = "Could not map memory";
static void GBASetActiveRegion(struct ARMMemory* memory, uint32_t region);
void GBAInit(struct GBA* gba) {
gba->errno = GBA_NO_ERROR;
gba->errstr = 0;
@ -45,6 +47,10 @@ void GBAMemoryInit(struct GBAMemory* memory) {
memory->p->errno = GBA_OUT_OF_MEMORY;
memory->p->errstr = GBA_CANNOT_MMAP;
}
memory->d.activeRegion = 0;
memory->d.activeMask = 0;
memory->d.setActiveRegion = GBASetActiveRegion;
}
void GBAMemoryDeinit(struct GBAMemory* memory) {
@ -71,6 +77,38 @@ void GBALoadROM(struct GBA* gba, int fd) {
// TODO: error check
}
static void GBASetActiveRegion(struct ARMMemory* memory, uint32_t address) {
struct GBAMemory* gbaMemory = (struct GBAMemory*) memory;
switch (address & ~OFFSET_MASK) {
case BASE_BIOS:
memory->activeRegion = gbaMemory->bios;
memory->activeMask = 0;
break;
case BASE_WORKING_RAM:
memory->activeRegion = gbaMemory->wram;
memory->activeMask = SIZE_WORKING_RAM - 1;
break;
case BASE_WORKING_IRAM:
memory->activeRegion = gbaMemory->iwram;
memory->activeMask = SIZE_WORKING_IRAM - 1;
break;
case BASE_CART0:
case BASE_CART0_EX:
case BASE_CART1:
case BASE_CART1_EX:
case BASE_CART2:
case BASE_CART2_EX:
memory->activeRegion = gbaMemory->rom;
memory->activeMask = SIZE_CART0 - 1;
break;
default:
memory->activeRegion = 0;
memory->activeMask = 0;
break;
}
}
int32_t GBALoad32(struct ARMMemory* memory, uint32_t address) {
struct GBAMemory* gbaMemory = (struct GBAMemory*) memory;

5
src/isa-arm.c
View File

@ -29,7 +29,7 @@ static inline void _immediate(struct ARMCore* cpu, uint32_t opcode) {
static const ARMInstruction _armTable[0x1000];
static ARMInstruction _ARMLoadInstructionARM(struct ARMMemory* memory, uint32_t address, uint32_t* opcodeOut) {
uint32_t opcode = memory->load32(memory, address);
uint32_t opcode = memory->activeRegion[(address & memory->activeMask) >> 2];
*opcodeOut = opcode;
return _armTable[((opcode >> 16) & 0xFF0) | ((opcode >> 4) & 0x00F)];
}
@ -127,7 +127,8 @@ void ARMStep(struct ARMCore* cpu) {
// Beware pre-processor antics
#define ARM_WRITE_PC \
cpu->gprs[ARM_PC] = (cpu->gprs[ARM_PC] & -WORD_SIZE_ARM) + WORD_SIZE_ARM
cpu->gprs[ARM_PC] = (cpu->gprs[ARM_PC] & -WORD_SIZE_ARM) + WORD_SIZE_ARM; \
cpu->memory->setActiveRegion(cpu->memory, cpu->gprs[ARM_PC]);
#define ARM_ADDITION_S(M, N, D) \
if (rd == ARM_PC && _ARMModeHasSPSR(cpu->cpsr.priv)) { \

11
src/main.c
View File

@ -2,8 +2,9 @@
#include "gba.h"
#include "isa-arm.h"
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <unistd.h>
int main(int argc, char** argv) {
struct GBA gba;
@ -11,9 +12,13 @@ int main(int argc, char** argv) {
int fd = open("test.rom", O_RDONLY);
GBALoadROM(&gba, fd);
gba.cpu.gprs[ARM_PC] = 0x08000004;
ARMStep(&gba.cpu);
ARMStep(&gba.cpu);
gba.memory.d.setActiveRegion(&gba.memory.d, gba.cpu.gprs[ARM_PC]);
int i;
for (i = 0; i < 1024 * 1024 * 16; ++i) {
ARMStep(&gba.cpu);
}
GBADeinit(&gba);
close(fd);
return 0;
}