Apple-1-Tools/reinette
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the Apple 1 Emulator

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ArthurFerreira2 2019-03-10 15:59:33 +01:00 committed by GitHub
parent f0e878b341
commit ac7501c83b
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1 changed files with 35 additions and 51 deletions
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reinette.c
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@ -159,7 +159,7 @@ static void IND(){ // INDirect - JMP ($ABCD) with page-boundary wraparound bug
static void IDX(){ // InDexed indirect X
uint16_t vector1 = ((readMem(reg.PC++) + reg.X) & 0xFF);
ope.address = readMem(vector1&0x00FF) | (readMem((vector1+1) & 0x00FF) << 8);
ope.address = readMem(vector1 & 0x00FF)|(readMem((vector1+1) & 0x00FF) << 8);
ope.value = readMem(ope.address);
}
@ -219,7 +219,8 @@ static void LDA(){ // LoaD Accumulator
static void LDX(){ // LoaD X
reg.X = ope.value;
setSZ(reg.X);}
setSZ(reg.X);
}
static void LDY(){ // LoaD Y
reg.Y = ope.value;
@ -362,20 +363,20 @@ static void RTI(){ // ReTurn from Interrupt
}
static void CMP(){ // Compare with A
setSZ((reg.A - ope.value) & 0xFF);
if (reg.A >= (ope.value & 0xFF)) reg.SR |= CARRY;
setSZ(reg.A - ope.value);
if (reg.A >= ope.value) reg.SR |= CARRY;
else reg.SR &= ~CARRY;
}
static void CPX(){ // Compare with X
setSZ((reg.X - ope.value) & 0xFF);
if (reg.X >= (ope.value & 0xFF)) reg.SR |= CARRY;
setSZ(reg.X - ope.value);
if (reg.X >= ope.value) reg.SR |= CARRY;
else reg.SR &= ~CARRY;
}
static void CPY(){ // Compare with Y
setSZ((reg.Y - ope.value) & 0xFF);
if (reg.Y >= (ope.value & 0xFF)) reg.SR |= CARRY;
setSZ(reg.Y - ope.value);
if (reg.Y >= ope.value) reg.SR |= CARRY;
else reg.SR &= ~CARRY;
}
@ -395,61 +396,43 @@ static void EOR(){ // Exclusive Or with A
}
static void BIT(){ // BIT with A - http://www.6502.org/tutorials/vflag.html
if (!(reg.A & ope.value)) reg.SR |= ZERO;
else reg.SR &= ~ZERO;
if (reg.A & ope.value) reg.SR &= ~ZERO;
else reg.SR |= ZERO;
reg.SR = (reg.SR & 0x3F) | (ope.value & 0xC0); // update SIGN & OVERFLOW
}
static void makeUpdates(uint8_t val){
if (ope.setAcc) reg.A = val;
else writeMem(ope.address, val);
ope.setAcc = false;
setSZ(val);
}
static void ASL(){ // Arithmetic Shift Left
uint16_t result = (ope.value << 1);
if (result & 0xFF00) reg.SR |= CARRY;
else reg.SR &= ~CARRY;
result &= 0xFF;
if (ope.setAcc){
reg.A = result;
ope.setAcc = false;
}
else writeMem(ope.address, result);
setSZ(result);
makeUpdates((uint8_t)(result & 0xFF));
}
static void LSR(){ // Logical Shift Right
uint8_t result8;
if (ope.value & 1) reg.SR |= CARRY;
else reg.SR &= ~CARRY;
result8 = (ope.value >> 1) & 0xFF;
if (ope.setAcc){
reg.A = result8;
ope.setAcc = false;
}
else writeMem(ope.address, result8);
setSZ(result8);
makeUpdates((uint8_t)((ope.value >> 1) & 0xFF));
}
static void ROL(){ // ROtate Left
uint16_t result = ((ope.value << 1) | (reg.SR & CARRY));
if (result & 0x100) reg.SR |= CARRY;
else reg.SR &= ~CARRY;
result &= 0xFF;
if (ope.setAcc){
reg.A = result;
ope.setAcc = false;
}
else writeMem(ope.address, result);
setSZ(result);
makeUpdates((uint8_t)(result & 0xFF));
}
static void ROR(){ // ROtate Right
uint16_t result = (ope.value >> 1) | ((reg.SR & CARRY) << 7);
if (ope.value & 0x1) reg.SR |= CARRY;
else reg.SR &= ~CARRY;
result &= 0xFF;
if (ope.setAcc){
reg.A = result;
ope.setAcc = false;
}
else writeMem(ope.address, result);
setSZ(result);
makeUpdates((uint8_t)(result & 0xFF));
}
static void ADC(){ // ADd with Carry
@ -484,7 +467,7 @@ static void UND(){ // UNDefined (not a valid or supported 6502 opcode)
// JUMP TABLES
static void (*instruction[])(void) = {
static void (*instruction[])(void) = {
BRK, ORA, UND, UND, UND, ORA, ASL, UND, PHP, ORA, ASL, UND, UND, ORA, ASL, UND,
BPL, ORA, UND, UND, UND, ORA, ASL, UND, CLC, ORA, UND, UND, UND, ORA, ASL, UND,
JSR, AND, UND, UND, BIT, AND, ROL, UND, PLP, AND, ROL, UND, BIT, AND, ROL, UND,
@ -542,23 +525,24 @@ int main(int argc, char *argv[]) {
// main loop
while(1){
for (i=0; i<100; i++){ // executes 100 instructions before a kbd scan
for (i=0; i<100; i++){ // execute 100 instructions before a kbd scan
opcode = readMem(reg.PC++); // FETCH and increment the Program Counter
addressing[opcode](); // DECODE operands against the addressing mode
instruction[opcode](); // EXEC the instruction
}
// keyboard controller
ch = getch(); // non blocking keybd read from ncurses
if (ch != ERR){
key = (uint8_t)ch; // getch() returns an int
if (key == 0x12) reset(); // CTRL-R, reset
else if (key == 0x02) BRK(); // CTRL-B, break
else if (!keyRdy){ // only if not already a key in wait
if (key == 0x0A) key = 0x0D; // LF (\n) to CR (\r)
if ((key == 0x7F) || (key == 0x08)) key = 0x5F; // DEL and BS to _
if ((key >= 0x61) && (key <= 0x7A)) key &= 0xDF; // to upper case
keyRdy = 0x80;
if (!keyRdy){ // only if not already a key in wait
if ((ch = getch()) != ERR){ // non blocking keybd read from ncurses
key = (uint8_t)ch; // getch() returns an int
if (key == 0x12) reset(); // CTRL-R, reset
else if (key == 0x02) BRK(); // CTRL-B, break
else {
if (key == 0x0A) key = 0x0D; // LF (\n) to CR (\r)
if ((key == 0x7F) || (key == 0x08)) key = 0x5F; // DEL and BS to _
if ((key >= 0x61) && (key <= 0x7A)) key &= 0xDF; // to upper case
keyRdy = 0x80;
}
}
}
}