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Add more framework for loading instructions

This commit is contained in:
Jeffrey Pfau 2013-04-03 22:34:49 -07:00
parent 009bef870c
commit bf72532715
2 changed files with 64 additions and 1 deletions
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41
src/arm.c
View File

@ -1,5 +1,38 @@
#include "arm.h"
static void _ARMSetMode(struct ARMCore*, enum ExecutionMode);
static ARMInstruction _ARMLoadInstructionARM(struct ARMMemory*, uint32_t address);
static ARMInstruction _ARMLoadInstructionThumb(struct ARMMemory*, uint32_t address);
static void _ARMSetMode(struct ARMCore* cpu, enum ExecutionMode executionMode) {
if (executionMode == cpu->executionMode) {
return;
}
cpu->executionMode = executionMode;
switch (executionMode) {
case MODE_ARM:
cpu->cpsr.t = 0;
cpu->instructionWidth = WORD_SIZE_ARM;
cpu->loadInstruction = _ARMLoadInstructionARM;
break;
case MODE_THUMB:
cpu->cpsr.t = 1;
cpu->instructionWidth = WORD_SIZE_THUMB;
cpu->loadInstruction = _ARMLoadInstructionThumb;
}
}
static ARMInstruction _ARMLoadInstructionARM(struct ARMMemory* memory, uint32_t address) {
int32_t opcode = memory->load32(memory, address);
return 0;
}
static ARMInstruction _ARMLoadInstructionThumb(struct ARMMemory* memory, uint32_t address) {
uint16_t opcode = memory->loadU16(memory, address);
return 0;
}
void ARMInit(struct ARMCore* cpu) {
int i;
for (i = 0; i < 16; ++i) {
@ -16,8 +49,16 @@ void ARMInit(struct ARMCore* cpu) {
cpu->memory = 0;
cpu->board = 0;
cpu->executionMode = MODE_THUMB;
_ARMSetMode(cpu, MODE_ARM);
}
void ARMAssociateMemory(struct ARMCore* cpu, struct ARMMemory* memory) {
cpu->memory = memory;
}
void ARMCycle(struct ARMCore* cpu) {
// TODO
ARMInstruction instruction = cpu->loadInstruction(cpu->memory, cpu->gprs[ARM_PC] - cpu->instructionWidth);
}

24
src/arm.h
View File

@ -24,6 +24,11 @@ enum PrivilegeMode {
MODE_SYSTEM = 0x1F
};
enum WordSize {
WORD_SIZE_ARM = 4,
WORD_SIZE_THUMB = 2
};
enum ExecutionVector {
BASE_RESET = 0x00000000,
BASE_UNDEF = 0x00000004,
@ -34,6 +39,9 @@ enum ExecutionVector {
BASE_FIQ = 0x0000001C
};
struct ARMCore;
typedef void (*ARMInstruction)(struct ARMCore*);
union PSR {
struct {
int exec : 4;
@ -51,7 +59,14 @@ union PSR {
int32_t packed;
};
struct ARMMemory;
struct ARMMemory {
int32_t (*load32)(struct ARMMemory*, uint32_t address);
int16_t (*load16)(struct ARMMemory*, uint32_t address);
uint16_t (*loadU16)(struct ARMMemory*, uint32_t address);
int8_t (*load8)(struct ARMMemory*, uint32_t address);
uint8_t (*loadU8)(struct ARMMemory*, uint32_t address);
};
struct ARMBoard;
struct ARMCore {
@ -64,11 +79,18 @@ struct ARMCore {
int32_t shifterOperand;
int32_t shifterCarryOut;
int instructionWidth;
ARMInstruction (*loadInstruction)(struct ARMMemory*, uint32_t address);
enum ExecutionMode executionMode;
struct ARMMemory* memory;
struct ARMBoard* board;
};
void ARMInit(struct ARMCore* cpu);
void ARMAssociateMemory(struct ARMCore* cpu, struct ARMMemory* memory);
void ARMCycle(struct ARMCore* cpu);
#endif