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Diffstat (limited to 'src/cpu')
-rw-r--r--src/cpu/6502.c11
-rw-r--r--src/cpu/instructions.c115
-rw-r--r--src/cpu/table.c1
3 files changed, 23 insertions, 104 deletions
diff --git a/src/cpu/6502.c b/src/cpu/6502.c
index 17796cf..ab8248e 100644
--- a/src/cpu/6502.c
+++ b/src/cpu/6502.c
@@ -33,10 +33,11 @@ void flagClear(byte flag){
// Functions which perform reusable routines for finding if a specific flag should be set.
void SetFlagN(byte x){
- if ((x & flag_N) == flag_N)
+ /*if ((x & flag_N) == flag_N)
SetFlag(flag_N, 1);
else
- SetFlag(flag_N, 0);
+ SetFlag(flag_N, 0);*/
+ P = (x & flag_N) | (P & ~flag_N);
}
//Perform prior to any changes
@@ -84,9 +85,11 @@ void SetMemory(address x, byte y){
byte GetStack() {
+ S--;
return GetMemory(0x01FF - S);
}
-void SetStack(byte z) {
- SetMemory(0x01FF - S, z);
+void SetStack(byte x) {
+ SetMemory(0x01FF - S, x);
+ S++;
}
diff --git a/src/cpu/instructions.c b/src/cpu/instructions.c
index 36e2a41..c043ac4 100644
--- a/src/cpu/instructions.c
+++ b/src/cpu/instructions.c
@@ -18,32 +18,27 @@ AddData idata;
void fLDA(Addressing addr, address val){
acc = idata.value;
- PC += idata.length;
+ SetFlagN(acc);
}
void fLDX(Addressing addr, address val){
X = idata.value;
- PC += idata.length;
}
void fLDY(Addressing addr, address val){
Y = idata.value;
- PC += idata.length;
}
void fSTA(Addressing addr, address val){
SetMemory(idata.add, acc);
- PC += idata.length;
}
void fSTX(Addressing addr, address val){
SetMemory(idata.add, X);
- PC += idata.length;
}
void fSTY(Addressing addr, address val){
SetMemory(idata.add, Y);
- PC += idata.length;
}
// Arithmetic Instructions
@@ -60,7 +55,6 @@ void fADC(Addressing addr, address val){
acc += idata.value;
SetFlagN(acc);
SetFlagZ(acc);
- PC += idata.length;
}
void fSBC(Addressing addr, address val){
@@ -75,7 +69,6 @@ void fSBC(Addressing addr, address val){
acc -= idata.value;
SetFlagN(acc);
SetFlagZ(acc);
- PC += idata.length;
}
//Increment and Decrement Instructions
@@ -86,21 +79,18 @@ void fINC(Addressing addr, address val){
SetMemory(idata.add, a);
SetFlagN(Memory[idata.add]);
SetFlagZ(Memory[idata.add]);
- PC += idata.length;
}
void fINX(Addressing addr, address val){
X++;
SetFlagN(X);
SetFlagZ(X);
- PC += idata.length;
}
void fINY(Addressing addr, address val){
Y++;
SetFlagN(Y);
SetFlagZ(Y);
- PC += idata.length;
}
void fDEC(Addressing addr, address val){
@@ -109,21 +99,18 @@ void fDEC(Addressing addr, address val){
SetMemory(idata.add, a);
SetFlagN(Memory[idata.add]);
SetFlagZ(Memory[idata.add]);
- PC += idata.length;
}
void fDEX(Addressing addr, address val){
X--;
SetFlagN(X);
SetFlagZ(X);
- PC += idata.length;
}
void fDEY(Addressing addr, address val){
Y--;
SetFlagN(Y);
SetFlagZ(Y);
- PC += idata.length;
}
// Logical Instructions
@@ -132,21 +119,18 @@ void fAND(Addressing addr, address val){
acc &= idata.value;
SetFlagN(acc);
SetFlagZ(acc);
- PC += idata.length;
}
void fORA(Addressing addr, address val){
acc |= idata.value;
SetFlagN(acc);
SetFlagZ(acc);
- PC += idata.length;
}
void fEOR(Addressing addr, address val){
acc ^= idata.value;
SetFlagN(acc);
SetFlagZ(acc);
- PC += idata.length;
}
// Jump, Branch, Compare, and Test Bits
@@ -157,59 +141,35 @@ void fJMP(Addressing addr, address val){
void fBCC(Addressing addr, address val){ //FINISH ALL BRANCH INSTRUCTIONS
//signed char val down to BVC
- if (getFlag(flag_C) == 0)
- PC += (char)val;
- else
- PC += idata.length;
+ if (getFlag(flag_C) == 0) PC += (char)val;
}
void fBCS(Addressing addr, address val){
- if (getFlag(flag_C) == 1)
- PC += (char)val;
- else
- PC += idata.length;
+ if (getFlag(flag_C) == 1) PC += (char)val;
}
void fBEQ(Addressing addr, address val){
- if (getFlag(flag_Z) == 1)
- PC += (char)val;
- else
- PC += idata.length;
+ if (getFlag(flag_Z) == 1) PC += (char)val;
}
void fBNE(Addressing addr, address val){
- if (getFlag(flag_Z) == 0)
- PC += (char)val;
- else
- PC += idata.length;
+ if (getFlag(flag_Z) == 0) PC += (char)val;
}
void fBMI(Addressing addr, address val){
- if (getFlag(flag_N) == 1)
- PC += (char)val;
- else
- PC += idata.length;
+ if (getFlag(flag_N) == 1) PC += (char)val;
}
void fBPL(Addressing addr, address val){
- if (getFlag(flag_N) == 0)
- PC += (char)val;
- else
- PC += idata.length;
+ if (getFlag(flag_N) == 0) PC += (char)val;
}
void fBVS(Addressing addr, address val){
- if (getFlag(flag_V) == 1)
- PC += (char)val;
- else
- PC += idata.length;
+ if (getFlag(flag_V) == 1) PC += (char)val;
}
void fBVC(Addressing addr, address val){
- if (getFlag(flag_V) == 0)
- PC += (char)val;
- else
- PC += idata.length;
+ if (getFlag(flag_V) == 0) PC += (char)val;
}
void fCMP(Addressing addr, address val){
@@ -222,7 +182,6 @@ void fCMP(Addressing addr, address val){
else if (acc > idata.value){
flagClear(flag_N); flagClear(flag_Z); flagSet(flag_C);
}
- PC += idata.length;
}
void fCPX(Addressing addr, address val){
@@ -235,7 +194,6 @@ void fCPX(Addressing addr, address val){
else if (X > idata.value){
flagClear(flag_N); flagClear(flag_Z); flagSet(flag_C);
}
- PC += idata.length;
}
void fCPY(Addressing addr, address val){
@@ -248,20 +206,18 @@ void fCPY(Addressing addr, address val){
else if (Y > idata.value){
flagClear(flag_N); flagClear(flag_Z); flagSet(flag_C);
}
- PC += idata.length;
}
//NEED TO DOUBLE CHECK THIS INSTRUCTION
void fBIT(Addressing addr, address val){
- SetFlag(flag_N, (idata.value & flag_N));
- SetFlag(flag_V, (idata.value & flag_V));
+ SetFlag(flag_N, (idata.value & flag_N)?1:0);
+ SetFlag(flag_V, (idata.value & flag_V)?1:0);
if (((idata.value & flag_N) & (idata.value & flag_V)) == 0) {
flagSet(flag_Z);
} else {
flagSet(flag_Z);
}
- PC += idata.length;
}
// Shift and Rotate Instructions
@@ -271,7 +227,6 @@ void fASL(Addressing addr, address val){
acc = (idata.value << 1);
SetFlagN(acc);
SetFlagZ(acc);
- PC += idata.length;
}
void fLSR(Addressing addr, address val){
@@ -279,7 +234,6 @@ void fLSR(Addressing addr, address val){
acc = (idata.value >> 1);
SetFlagN(acc);
SetFlagZ(acc);
- PC += idata.length;
}
void fROL(Addressing addr, address val){
@@ -288,7 +242,6 @@ void fROL(Addressing addr, address val){
acc |= (getFlag(flag_C) * 0x01);
SetFlagN(acc);
SetFlagZ(acc);
- PC += idata.length;
}
void fROR(Addressing addr, address val){
@@ -297,7 +250,6 @@ void fROR(Addressing addr, address val){
acc |= (getFlag(flag_C) * 0x80);
SetFlagN(acc);
SetFlagZ(acc);
- PC += idata.length;
}
// Transfer Instructions
@@ -306,90 +258,69 @@ void fTAX(Addressing addr, address val){
X = acc;
//SetFlagN(X);
//SetFlagZ(X);
- PC += idata.length;
}
void fTAY(Addressing addr, address val){
Y = acc;
//SetFlagN(Y);
//SetFlagZ(Y);
- PC += idata.length;
}
void fTXA(Addressing addr, address val){
acc = X;
SetFlagN(acc);
SetFlagZ(acc);
- PC += idata.length;
}
void fTYA(Addressing addr, address val){
acc = Y;
SetFlagN(acc);
SetFlagZ(acc);
- PC += idata.length;
}
// Stack Instructions
void fTSX(Addressing addr, address val){
X = S;
- PC += idata.length;
}
void fTXS(Addressing addr, address val){
S = X;
- PC += idata.length;
}
void fPHA(Addressing addr, address val){
SetStack(acc);
- S++;
- PC += idata.length;
}
void fPHP(Addressing addr, address val){
SetStack(P);
- S++;
- PC += idata.length;
}
void fPLA(Addressing addr, address val){
- S--;
acc = GetStack();
- PC += idata.length;
}
void fPLP(Addressing addr, address val){
- S--;
P = GetStack();
- PC += idata.length;
}
// Subroutine Instructions
// NEED TO FINISH THESE
void fJSR(Addressing addr, address val){
- SetStack(((PC-1) & 0xFF00) >> 8);
- S++;
- SetStack((PC-1) & 0x00FF);
- S++;
+ SetStack((PC+3) >> 8);
+ SetStack((PC+3) & 0x00FF);
PC = idata.add;
}
void fRTS(Addressing addr, address val){
- S--;
- PC = (address)(GetStack() + 1);
- S--;
+ PC = (address)(GetStack()) - 1;
PC += ((address)(GetStack())) << 8;
}
void fRTI(Addressing addr, address val){
- S--;
P = GetStack(); //NEED TO FIX
- S--;
- PC = (address)(GetStack());
- S--;
+ PC = (address)(GetStack());
PC += (address)(GetStack() << 8);
}
@@ -397,57 +328,41 @@ void fRTI(Addressing addr, address val){
void fCLC(Addressing addr, address val){
flagClear(flag_C);
- PC += idata.length;
}
void fCLD(Addressing addr, address val){
flagClear(flag_D);
- PC += idata.length;
}
void fCLI(Addressing addr, address val){
flagClear(flag_I);
- PC += idata.length;
}
void fCLV(Addressing addr, address val){
flagClear(flag_V);
- PC += idata.length;
}
void fSEC(Addressing addr, address val){
flagSet(flag_C);
- PC += idata.length;
}
void fSED(Addressing addr, address val){
flagSet(flag_D);
- PC += idata.length;
}
void fSEI(Addressing addr, address val){
flagSet(flag_I);
- PC += idata.length;
}
// NOP/BRK Instructions
void fNOP(Addressing addr, address val){
- PC += idata.length;
}
void fBRK(Addressing addr, address val){
SetStack((((PC+2) & 0xFF00) >> 8));
- S++;
SetStack((PC+2) & 0x00FF);
- S++;
SetStack(P);
- S++;
PC = (address)(GetMemory(0xFFFE));
PC += ((address)(GetMemory(0xFFFF)) << 8);
}
-
-#ifdef ILLEGAL_INSTRUCTIONS
-
-
-#endif
diff --git a/src/cpu/table.c b/src/cpu/table.c
index 27ec8f2..ca14c1c 100644
--- a/src/cpu/table.c
+++ b/src/cpu/table.c
@@ -35,6 +35,7 @@ void CallInstructionTable(int i, address val){
// Perform function
func(*r, val);
+ PC += idata.length;
}
void SetInstructionTable(int i, uintptr_t p, Addressing r){
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-23 16:35:28 +0000