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Implement immediate shifter

This commit is contained in:
Jeffrey Pfau 2013-04-05 00:43:47 -07:00
parent c07df4a337
commit cd07dee7b1
1 changed files with 18 additions and 7 deletions
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25
src/arm.c
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@ -1,5 +1,8 @@
#include "arm.h"
#define ARM_SIGN(I) ((I) >> 31)
#define ARM_ROR(I, ROTATE) (((I) >> ROTATE) | (I << (32 - ROTATE)))
static inline void _ARMSetMode(struct ARMCore*, enum ExecutionMode);
static ARMInstruction _ARMLoadInstructionARM(struct ARMMemory*, uint32_t address, uint32_t* opcodeOut);
static ARMInstruction _ARMLoadInstructionThumb(struct ARMMemory*, uint32_t address, uint32_t* opcodeOut);
@ -17,7 +20,15 @@ static inline void _barrelShift(struct ARMCore* cpu, uint32_t opcode) {
}
static inline void _immediate(struct ARMCore* cpu, uint32_t opcode) {
// TODO
int rotate = (opcode & 0x00000F00) >> 7;
int immediate = opcode & 0x000000FF;
if (!rotate) {
cpu->shifterOperand = immediate;
cpu->shifterCarryOut = cpu->cpsr.c;
} else {
cpu->shifterOperand = ARM_ROR(immediate, rotate);
cpu->shifterCarryOut = ARM_SIGN(cpu->shifterOperand);
}
}
static const ARMInstruction armTable[0xF000];
@ -89,10 +100,10 @@ inline void ARMCycle(struct ARMCore* cpu) {
// Instruction definitions
// Beware pre-processor antics
#define ARM_CARRY_FROM(M, N, D) ((((M) | (N)) >> 31) && !((D) >> 31))
#define ARM_CARRY_FROM(M, N, D) ((ARM_SIGN((M) | (N))) && !(ARM_SIGN(D)))
#define ARM_BORROW_FROM(M, N, D) (((uint32_t) (M)) >= ((uint32_t) (N)))
#define ARM_V_ADDITION(M, N, D) (!(((M) ^ (N)) >> 31) && (((M) ^ (D)) >> 31) && (((N) ^ (D)) >> 31))
#define ARM_V_SUBTRACTION(M, N, D) ((((M) ^ (N)) >> 31) && (((M) ^ (D)) >> 31))
#define ARM_V_ADDITION(M, N, D) (!(ARM_SIGN((M) ^ (N))) && (ARM_SIGN((M) ^ (D))) && (ARM_SIGN((N) ^ (D))))
#define ARM_V_SUBTRACTION(M, N, D) ((ARM_SIGN((M) ^ (N))) && (ARM_SIGN((M) ^ (D))))
#define ARM_COND_EQ (cpu->cpsr.z)
#define ARM_COND_NE (!cpu->cpsr.z)
@ -115,7 +126,7 @@ inline void ARMCycle(struct ARMCore* cpu) {
cpu->cpsr = cpu->spsr; \
_ARMReadCPSR(cpu); \
} else { \
cpu->cpsr.n = (D) >> 31; \
cpu->cpsr.n = ARM_SIGN(D); \
cpu->cpsr.z = !(D); \
cpu->cpsr.c = ARM_CARRY_FROM(M, N, D); \
cpu->cpsr.v = ARM_V_ADDITION(M, N, D); \
@ -126,7 +137,7 @@ inline void ARMCycle(struct ARMCore* cpu) {
cpu->cpsr = cpu->spsr; \
_ARMReadCPSR(cpu); \
} else { \
cpu->cpsr.n = (D) >> 31; \
cpu->cpsr.n = ARM_SIGN(D); \
cpu->cpsr.z = !(D); \
cpu->cpsr.c = ARM_BORROW_FROM(M, N, D); \
cpu->cpsr.v = ARM_V_SUBTRACTION(M, N, D); \
@ -137,7 +148,7 @@ inline void ARMCycle(struct ARMCore* cpu) {
cpu->cpsr = cpu->spsr; \
_ARMReadCPSR(cpu); \
} else { \
cpu->cpsr.n = (D) >> 31; \
cpu->cpsr.n = ARM_SIGN(D); \
cpu->cpsr.z = !(D); \
cpu->cpsr.c = cpu->shifterCarryOut; \
}