261 lines
8.1 KiB
C
261 lines
8.1 KiB
C
#include <Z/constants/pointer.h> /* Z_NULL */
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#include <Z80.h>
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#include <string.h>
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#include <stdio.h>
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#include <stdlib.h>
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#define CYCLES_PER_FRAME 69888
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#define CYCLES_AT_INT 24
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#define CYCLES_PER_INT 32
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#define ROM_SIZE 0x8000 /* 32 KiB */
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#define MEMORY_SIZE 0xFFFF /* 64 KiB */
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typedef struct {
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void* context;
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zuint8 (* read)(void *context);
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void (* write)(void *context, zuint8 value);
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} Device;
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typedef struct {
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zusize cycles;
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zuint8 memory[65536];
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Z80 cpu;
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Device* devices;
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zusize device_count;
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} Machine;
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static zuint8 machine_cpu_read(Machine *self, zuint16 address) {
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return address < MEMORY_SIZE ? self->memory[address] : 0xFF;
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}
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static void machine_cpu_write(Machine *self, zuint16 address, zuint8 value) {
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if (address >= ROM_SIZE && address < MEMORY_SIZE)
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self->memory[address] = value;
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}
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static zuint8 machine_cpu_in(Machine *self, zuint16 port) {
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// Pat80 has 8 devices, decoded based on the 3 most significant IO addr bits.
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// Note the Z80 has 16 bit address bus, but only the first 8 are used as IO addr,
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// so the 3 most significant IO addr bits in this case are A7, A6, A5. The bits
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// A4-A0 may be used by the single device, at its own discretion.
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zuint16 bitmask = 7; // 0000000000000111
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int decoded = port & bitmask;
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if (decoded <= 0x1F) {
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// Port 0 (0x00 to 0x1F): terminal
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//printf("TERMINAL_READ");
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//return 'H';
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return 0x00;
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}
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if (decoded <= 0x3F) {
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// Port 1 (0x20 to 0x3F): sound card (sn76489)
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printf("\nsound_cmd[IN]: Not supported!\n");
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return 0x00;
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}
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if (decoded <= 0x5F) {
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// Port 2 (0x40 to 0x5F)
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printf("IO_ERROR_IN: No device at port 2\n");
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return 0x00;
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}
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if (decoded <= 0x7F) {
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// Port 3 (0x60 to 0x7F)
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printf("IO_ERROR_IN: No device at port 3\n");
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return 0x00;
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}
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if (decoded <= 0x9F) {
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// Port 4 (0x80 to 0x9F)
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printf("IO_ERROR_IN: No device at port 4\n");
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return 0x00;
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}
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if (decoded <= 0x5F) {
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// Port 5 (0xA0 to 0xBF)
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printf("IO_ERROR_IN: No device at port 5\n");
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return 0x00;
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}
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if (decoded <= 0x5F) {
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// Port 6 (0xC0 to 0xDF)
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printf("IO_ERROR_IN: No device at port 6\n");
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return 0x00;
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}
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if (decoded <= 0x5F) {
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// Port 7 (0xE0 to 0xFF)
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printf("IO_ERROR_IN: No device at port 7\n");
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} else {
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printf("IO_ERROR_IN: Invalid port address: %#04x\n", port);
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}
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}
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static void machine_cpu_out(Machine *self, zuint16 port, zuint8 value) {
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// Pat80 has 8 devices, decoded based on the 3 most significant IO addr bits.
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// Note the Z80 has 16 bit address bus, but only the first 8 are used as IO addr,
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// so the 3 most significant IO addr bits in this case are A7, A6, A5. The bits
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// A4-A0 may be used by the single device, at its own discretion.
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zuint16 bitmask = 0xE0; // 0000000011100000
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int decoded = port & bitmask;
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if (decoded <= 0x1F) {
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// Port 0 (0x00 to 0x1F): terminal
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printf("%c", value);
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} else if (decoded <= 0x3F) {
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// Port 1 (0x20 to 0x3F): sound card (sn76489)
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printf("\nsound_cmd[%#04x]\n", value);
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} else if (decoded <= 0x5F) {
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// Port 2 (0x40 to 0x5F)
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printf("IO_ERROR_OUT: No device at port 2\n");
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} else if (decoded <= 0x7F) {
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// Port 3 (0x60 to 0x7F)
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printf("IO_ERROR_OUT: No device at port 3\n");
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} else if (decoded <= 0x9F) {
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// Port 4 (0x80 to 0x9F)
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printf("IO_ERROR_OUT: No device at port 4\n");
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} else if (decoded <= 0x5F) {
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// Port 5 (0xA0 to 0xBF)
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printf("IO_ERROR_OUT: No device at port 5\n");
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} else if (decoded <= 0x5F) {
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// Port 6 (0xC0 to 0xDF)
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printf("IO_ERROR_OUT: No device at port 6\n");
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} else if (decoded <= 0x5F) {
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// Port 7 (0xE0 to 0xFF)
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printf("IO_ERROR_OUT: No device at port 7\n");
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} else {
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printf("IO_ERROR_OUT: Invalid port address: %#04x\n", port);
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}
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}
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void machine_initialize(Machine *self) {
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self->cpu.context = self;
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self->cpu.fetch_opcode =
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self->cpu.fetch =
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self->cpu.nop =
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self->cpu.read = (Z80Read )machine_cpu_read;
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self->cpu.write = (Z80Write)machine_cpu_write;
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self->cpu.in = (Z80Read )machine_cpu_in;
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self->cpu.out = (Z80Write)machine_cpu_out;
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self->cpu.halt = Z_NULL;
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self->cpu.nmia = Z_NULL;
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self->cpu.inta = Z_NULL;
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self->cpu.int_fetch = Z_NULL;
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self->cpu.ld_i_a = Z_NULL;
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self->cpu.ld_r_a = Z_NULL;
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self->cpu.reti = Z_NULL;
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self->cpu.retn = Z_NULL;
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self->cpu.hook = Z_NULL;
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self->cpu.illegal = Z_NULL;
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self->cpu.options = Z80_MODEL_ZILOG_NMOS;
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/* Create and initialize devices... */
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}
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void machine_power(Machine *self, zbool state) {
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if (state)
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{
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self->cycles = 0;
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memset(self->memory, 0, MEMORY_SIZE);
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}
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z80_power(&self->cpu, state);
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}
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void machine_reset(Machine *self) {
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z80_instant_reset(&self->cpu);
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}
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void machine_run(Machine *self) {
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z80_run(&self->cpu, Z80_MAXIMUM_CYCLES);
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}
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// void machine_run_frame(Machine *self)
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// {
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// /* CPU cycles before the INT signal */
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// self->cycles += z80_execute(&self->cpu, CYCLES_AT_INT - self->cycles);
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// /* CPU cycles during the INT signal */
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// z80_int(&self->cpu, Z_TRUE);
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// self->cycles += z80_run(&self->cpu, (CYCLES_AT_INT + CYCLES_PER_INT) - self->cycles);
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// z80_int(&self->cpu, Z_FALSE);
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// /* CPU cycles after the INT signal */
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// self->cycles += z80_execute(&self->cpu, CYCLES_PER_FRAME - self->cycles);
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// self->cycles -= CYCLES_PER_FRAME;
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// }
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// TEST IMPLEM DEVICE
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zuint8 device_terminal_read(void *context) {
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return 'H';
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//return 0;
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}
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void device_terminal_write(void *context, zuint8 value) {
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printf("%c", value);
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}
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zuint8 device_sound_read(void *context) {
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return 0;
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}
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void device_sound_write(void *context, zuint8 value) {
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printf("sound[%c]\n", value);
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}
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// TEST IMPLEM DEVICE
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int main(int argc, char *argv[]) {
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// Parse arguments
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if (argc < 2) {
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printf("Usage: %s [romFile]\n", argv[0]);
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exit(0);
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}
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char* romFilePath = argv[1];
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// Setup virtual Pat80 computer
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Z80 pat80Cpu = {};
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Machine pat80 = {
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/*zusize*/ .cycles = 100000,
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/*Z80*/ .cpu = pat80Cpu
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};
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machine_initialize(&pat80);
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machine_power(&pat80, Z_TRUE);
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// Load ROM into memory
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FILE *romFile;
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romFile = fopen(romFilePath,"rb");
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if (romFile == NULL) {
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printf("Unable to open rom file at %s", romFilePath);
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exit(1);
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}
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fread(&pat80.memory,ROM_SIZE,1,romFile); // load rom from file into memory, up >
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fclose(romFile);
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// Declare system devices
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Device patoTerminal = {
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.read = *device_terminal_read,
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.write = *device_terminal_write,
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};
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Device patoSound = {
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.read = *device_sound_read,
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.write = *device_sound_write,
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};
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Device patoDevices[2] = {
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patoTerminal, // Port 0 (0x00 to 0x1F)
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patoSound // Port 1 (0x20 to 0x3F)
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};
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pat80.devices = patoDevices;
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pat80.device_count = 2;
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machine_reset(&pat80);
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machine_run(&pat80);
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}
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