6502
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6502-emu
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Made variable names slightly more consistent

This commit is contained in:
DavidBuchanan314 2017-01-03 20:18:36 +00:00
parent 12f80f409c
commit 1da995b11a
6 changed files with 78 additions and 149 deletions
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14
6502-emu.c
View File

@ -6,7 +6,7 @@
#include "6502.h"
#include "6850.h"
struct termios oldTermios;
struct termios initial_termios;
void step_delay()
{
@ -32,17 +32,17 @@ void run_cpu()
void restore_stdin()
{
tcsetattr(0, TCSANOW, &oldTermios);
tcsetattr(0, TCSANOW, &initial_termios);
}
void raw_stdin()
{
struct termios newTermios;
struct termios new_termios;
tcgetattr(0, &oldTermios);
newTermios = oldTermios;
cfmakeraw(&newTermios);
tcsetattr(0, TCSANOW, &newTermios);
tcgetattr(0, &initial_termios);
new_termios = initial_termios;
cfmakeraw(&new_termios);
tcsetattr(0, TCSANOW, &new_termios);
atexit(restore_stdin);
}

120
6502.c
View File

@ -14,12 +14,12 @@ int jumping; // used to check that we don't need to increment the PC after a jum
/* Flag Checks */
static inline void Nflag(int8_t val)
static inline void N_flag(int8_t val)
{
SR.bits.sign = val < 0;
}
static inline void Zflag(uint8_t val)
static inline void Z_flag(uint8_t val)
{
SR.bits.zero = val == 0;
}
@ -40,12 +40,12 @@ static inline uint8_t stack_pull()
static inline uint8_t * read_ptr()
{
return readAddr = get_ptr[inst.mode]();
return read_addr = get_ptr[inst.mode]();
}
static inline uint8_t * write_ptr()
{
return writeAddr = get_ptr[inst.mode]();
return write_addr = get_ptr[inst.mode]();
}
/* Instruction Implementations */
@ -57,15 +57,15 @@ static void inst_ADC()
SR.bits.carry = tmp > 0xFF;
SR.bits.overflow = ((A^tmp)&(operand^tmp)&0x80) != 0;
A = tmp & 0xFF;
Nflag(A);
Zflag(A);
N_flag(A);
Z_flag(A);
}
static void inst_AND()
{
A &= * read_ptr();
Nflag(A);
Zflag(A);
N_flag(A);
Z_flag(A);
}
static void inst_ASL()
@ -73,8 +73,8 @@ static void inst_ASL()
uint8_t tmp = * read_ptr();
SR.bits.carry = (tmp & 0x80) != 0;
tmp <<= 1;
Nflag(tmp);
Zflag(tmp);
N_flag(tmp);
Z_flag(tmp);
* write_ptr() = tmp;
}
@ -102,8 +102,8 @@ static void inst_BEQ()
static void inst_BIT()
{
uint8_t tmp = * read_ptr();
Nflag(tmp);
Zflag(tmp & A);
N_flag(tmp);
Z_flag(tmp & A);
SR.bits.overflow = (tmp & 0x40) != 0;
}
@ -180,8 +180,8 @@ static void inst_CMP()
{
uint8_t operand = * read_ptr();
uint8_t tmpDiff = A - operand;
Nflag(tmpDiff);
Zflag(tmpDiff);
N_flag(tmpDiff);
Z_flag(tmpDiff);
SR.bits.carry = A >= operand;
}
@ -189,8 +189,8 @@ static void inst_CPX()
{
uint8_t operand = * read_ptr();
uint8_t tmpDiff = X - operand;
Nflag(tmpDiff);
Zflag(tmpDiff);
N_flag(tmpDiff);
Z_flag(tmpDiff);
SR.bits.carry = X >= operand;
}
@ -198,8 +198,8 @@ static void inst_CPY()
{
uint8_t operand = * read_ptr();
uint8_t tmpDiff = Y - operand;
Nflag(tmpDiff);
Zflag(tmpDiff);
N_flag(tmpDiff);
Z_flag(tmpDiff);
SR.bits.carry = Y >= operand;
}
@ -207,53 +207,53 @@ static void inst_DEC()
{
uint8_t tmp = * read_ptr();
tmp--;
Nflag(tmp);
Zflag(tmp);
N_flag(tmp);
Z_flag(tmp);
* write_ptr() = tmp;
}
static void inst_DEX()
{
X--;
Nflag(X);
Zflag(X);
N_flag(X);
Z_flag(X);
}
static void inst_DEY()
{
Y--;
Nflag(Y);
Zflag(Y);
N_flag(Y);
Z_flag(Y);
}
static void inst_EOR()
{
A ^= * read_ptr();
Nflag(A);
Zflag(A);
N_flag(A);
Z_flag(A);
}
static void inst_INC()
{
uint8_t tmp = * read_ptr();
tmp++;
Nflag(tmp);
Zflag(tmp);
N_flag(tmp);
Z_flag(tmp);
* write_ptr() = tmp;
}
static void inst_INX()
{
X++;
Nflag(X);
Zflag(X);
N_flag(X);
Z_flag(X);
}
static void inst_INY()
{
Y++;
Nflag(Y);
Zflag(Y);
N_flag(Y);
Z_flag(Y);
}
static void inst_JMP()
@ -275,22 +275,22 @@ static void inst_JSR()
static void inst_LDA()
{
A = * read_ptr();
Nflag(A);
Zflag(A);
N_flag(A);
Z_flag(A);
}
static void inst_LDX()
{
X = * read_ptr();
Nflag(X);
Zflag(X);
N_flag(X);
Z_flag(X);
}
static void inst_LDY()
{
Y = * read_ptr();
Nflag(Y);
Zflag(Y);
N_flag(Y);
Z_flag(Y);
}
static void inst_LSR()
@ -298,8 +298,8 @@ static void inst_LSR()
uint8_t tmp = * read_ptr();
SR.bits.carry = tmp & 1;
tmp >>= 1;
Nflag(tmp);
Zflag(tmp);
N_flag(tmp);
Z_flag(tmp);
* write_ptr() = tmp;
}
@ -311,8 +311,8 @@ static void inst_NOP()
static void inst_ORA()
{
A |= * read_ptr();
Nflag(A);
Zflag(A);
N_flag(A);
Z_flag(A);
}
static void inst_PHA()
@ -329,8 +329,8 @@ static void inst_PHP()
static void inst_PLA()
{
A = stack_pull();
Nflag(A);
Zflag(A);
N_flag(A);
Z_flag(A);
}
static void inst_PLP()
@ -345,8 +345,8 @@ static void inst_ROL()
tmp |= SR.bits.carry & 1;
SR.bits.carry = tmp > 0xFF;
tmp &= 0xFF;
Nflag(tmp);
Zflag(tmp);
N_flag(tmp);
Z_flag(tmp);
* write_ptr() = tmp;
}
@ -356,8 +356,8 @@ static void inst_ROR()
tmp |= SR.bits.carry << 8;
SR.bits.carry = tmp & 1;
tmp >>= 1;
Nflag(tmp);
Zflag(tmp);
N_flag(tmp);
Z_flag(tmp);
* write_ptr() = tmp;
}
@ -386,8 +386,8 @@ static void inst_SBC()
SR.bits.carry = tmp > 0xFF;
SR.bits.overflow = ((A^tmp)&(operand^tmp)&0x80) != 0;
A = tmp & 0xFF;
Nflag(A);
Zflag(A);
N_flag(A);
Z_flag(A);
}
static void inst_SEC()
@ -424,29 +424,29 @@ static void inst_STY()
static void inst_TAX()
{
X = A;
Nflag(X);
Zflag(X);
N_flag(X);
Z_flag(X);
}
static void inst_TAY()
{
Y = A;
Nflag(Y);
Zflag(Y);
N_flag(Y);
Z_flag(Y);
}
static void inst_TSX()
{
X = SP;
Nflag(X);
Zflag(X);
N_flag(X);
Z_flag(X);
}
static void inst_TXA()
{
A = X;
Nflag(A);
Zflag(A);
N_flag(A);
Z_flag(A);
}
static void inst_TXS()
@ -457,8 +457,8 @@ static void inst_TXS()
static void inst_TYA()
{
A = Y;
Nflag(A);
Zflag(A);
N_flag(A);
Z_flag(A);
}
/* Addressing Implementations */

4
6502.h
View File

@ -16,8 +16,8 @@ uint8_t Y;
uint16_t PC;
uint8_t SP; // points to first empty stack location
void * readAddr;
void * writeAddr;
void * read_addr;
void * write_addr;
struct StatusBits{
int carry:1; // bit 0

16
6850.c
View File

@ -15,7 +15,7 @@ void init_uart() {
uart_SR.bits.TDRE = 1; // we are always ready to output data
uart_SR.bits.RDRF = 0;
incomingChar = 0;
incoming_char = 0;
}
@ -27,22 +27,22 @@ int stdin_ready() {
}
void step_uart() {
if (writeAddr == &memory[DATA_ADDR]) {
if (write_addr == &memory[DATA_ADDR]) {
putchar(memory[DATA_ADDR]);
fflush(stdout);
writeAddr = NULL;
} else if (readAddr == &memory[DATA_ADDR]) {
write_addr = NULL;
} else if (read_addr == &memory[DATA_ADDR]) {
uart_SR.bits.RDRF = 0;
readAddr = NULL;
read_addr = NULL;
}
/* update input register if empty */
if ((n++ % 10000) == 0) { // polling stdin every cycle is performance intensive. This is a bit of a dirty hack.
if (!uart_SR.bits.RDRF && stdin_ready()) { // the real hardware has no buffer. Remote the RDRF check for more accurate emulation.
if (read(0, &incomingChar, 1) != 1) {
if (read(0, &incoming_char, 1) != 1) {
printf("Warning: read() returned 0\n");
}
if (incomingChar == 0x18) { // CTRL+X
if (incoming_char == 0x18) { // CTRL+X
printf("\r\n");
exit(0);
}
@ -50,6 +50,6 @@ void step_uart() {
}
}
memory[DATA_ADDR] = incomingChar;
memory[DATA_ADDR] = incoming_char;
memory[CTRL_ADDR] = uart_SR.byte;
}

2
6850.h
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@ -19,7 +19,7 @@ union UartStatusReg {
union UartStatusReg uart_SR;
uint8_t incomingChar;
uint8_t incoming_char;
void init_uart();

71
main.c
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@ -1,71 +0,0 @@
#include <stdio.h>
#include <stdlib.h>
#include <termios.h>
#include <time.h>
#include "6502.h"
#include "6850.h"
struct termios oldTermios;
void step_delay()
{
struct timespec req, rem;
req.tv_sec = 0;
req.tv_nsec = STEP_DURATION;
nanosleep(&req, &rem);
}
void run_cpu()
{
for (;;) {
// CPU timing is currently very far from being cycle-accurate
for (int i = 0; i < (CPU_FREQ / (ONE_SECOND / STEP_DURATION)); i++) {
step_cpu();
step_uart();
}
step_delay(); // remove this for more speed
}
}
void restore_stdin()
{
tcsetattr(0, TCSANOW, &oldTermios);
}
void raw_stdin()
{
struct termios newTermios;
tcgetattr(0, &oldTermios);
newTermios = oldTermios;
cfmakeraw(&newTermios);
tcsetattr(0, TCSANOW, &newTermios);
atexit(restore_stdin);
}
int main(int argc, char *argv[])
{
if (argc != 2) {
printf("Usage: %s file.rom\n", argv[0]);
printf("The first 16k of \"file.rom\" is loaded into the last 16k of memory.\n");
return EXIT_FAILURE;
}
if (load_rom(argv[1]) != 0) {
printf("Error loading \"%s\".\n", argv[1]);
return EXIT_FAILURE;
}
raw_stdin(); // allow individual keystrokes to be detected
init_tables();
init_uart();
reset_cpu();
run_cpu();
return EXIT_SUCCESS;
}