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Fixes #17 - Clean up PIA code

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This commit is contained in:
Stefan Arentz 2016-11-16 21:06:35 -05:00
parent 1fd0206de5
commit d6bb1e5371
2 changed files with 44 additions and 18 deletions
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49
pia.c
View File

@ -29,8 +29,10 @@
#include "cpu.h"
#include "pia.h"
// This implements a 6820 Peripheral I/O Adapter. On the Apple I this
// is what connects the keyboard and display logic to the CPU.
static void pia_dsp_write(uint8_t b) {
//fprintf(stderr, "PIA: Sending to display: %.2x / %.2x\n", b, b & 0x7f);
b &= 0b01111111;
if (b == '\r') {
b = '\n';
@ -39,14 +41,6 @@ static void pia_dsp_write(uint8_t b) {
refresh();
}
/* static int pia_kbd_read() { */
/* int c = getch(); */
/* } */
/* static uint8_t pia_kbd_read() { */
/* return getchar(); */
/* } */
void pia_init(struct pia_t *pia) {
initscr();
raw();
@ -63,12 +57,16 @@ void pia_trace(struct pia_t *pia, uint8_t trace) {
uint8_t pia_read(struct cpu_t *cpu, struct mem_t *mem, uint16_t addr) {
struct pia_t *pia = (struct pia_t*) mem->obj;
uint8_t result = 0;
switch (addr) {
case 0xd010: /* KBD */
case EWM_A1_PIA6820_KBD: {
result = pia->a;
break;
case 0xd011: /* KBDCR */ {
}
case EWM_A1_PIA6820_KBDCR: {
int c = getch();
if (c != ERR) {
/* TODO: Remove this, this is not how we want to stop the emulator */
@ -78,42 +76,57 @@ uint8_t pia_read(struct cpu_t *cpu, struct mem_t *mem, uint16_t addr) {
if (c == '\n') {
c = '\r';
}
pia->a = c | 0x80;
pia->a = c | 0x80; // Set the high bit - WHat is up with the high bits. Document this.
}
result = (c == ERR) ? 0x00 : 0x80;
break;
}
case 0xd012: /* DSP */
case EWM_A1_PIA6820_DSP: {
result = 0;
break;
case 0xd013: /* DSPCR */
}
case EWM_A1_PIA6820_DSPCR: {
result = 0;
break;
}
}
if (pia->trace) {
fprintf(stderr, "PIA: READ BYTE %.2X FROM %.4X\n", result, addr);
}
return result;
}
void pia_write(struct cpu_t *cpu, struct mem_t *mem, uint16_t addr, uint8_t b) {
struct pia_t *pia = (struct pia_t*) mem->obj;
if (pia->trace) {
fprintf(stderr, "PIA: WRITING BYTE %.2X TO %.4X\n", b, addr);
}
switch (addr) {
case 0xd010: /* KBD */
case EWM_A1_PIA6820_KBD: { /* KBD */
break;
case 0xd011: /* KBDCR */
}
case EWM_A1_PIA6820_KBDCR: { /* KBDCR */
pia->cra = b;
break;
case 0xd012: /* DSP */
}
case EWM_A1_PIA6820_DSP: { /* DSP */
if (pia->crb != 0x00) { /* TODO: Check the actual flag */
pia_dsp_write(b);
}
break;
case 0xd013: /* DSPCR */
}
case EWM_A1_PIA6820_DSPCR: { /* DSPCR */
pia->crb = b;
break;
}
}
}

13
pia.h
View File

@ -26,6 +26,19 @@
#include <stdint.h>
#include "cpu.h"
#define EWM_PIA6820_DDRA 0
#define EWM_PIA6820_CTLA 1
#define EWM_PIA6820_DDRB 2
#define EWM_PIA6820_CTLB 3
#define EWM_A1_PIA6820_ADDR 0xd010
#define EWM_A1_PIA6820_LENGTH 0x0100
#define EWM_A1_PIA6820_KBD (EWM_A1_PIA6820_ADDR + EWM_PIA6820_DDRA)
#define EWM_A1_PIA6820_KBDCR (EWM_A1_PIA6820_ADDR + EWM_PIA6820_CTLA)
#define EWM_A1_PIA6820_DSP (EWM_A1_PIA6820_ADDR + EWM_PIA6820_DDRB)
#define EWM_A1_PIA6820_DSPCR (EWM_A1_PIA6820_ADDR + EWM_PIA6820_CTLB)
struct pia_t {
uint8_t a;
uint8_t cra;