3b1emu: src/main.c@724d2f6deb37 (annotated)

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src/main.c@724d2f6deb37 (annotated)

src/main.c

Wed, 01 Dec 2010 22:11:06 +0000

author: Philip Pemberton <philpem@philpem.me.uk>
date: Wed, 01 Dec 2010 22:11:06 +0000
changeset 24: 724d2f6deb37
parent 23: 3d964a6aa59b
child 25: 49526038b0fb
permissions: -rw-r--r--

add VRAM emulation

 #include <stdio.h>
 #include <stdlib.h>
 #include <stdint.h>
 #include <stdbool.h>
 #include <malloc.h>
 #include <string.h>
 #include "SDL.h"
 #include "musashi/m68k.h"
 #include "version.h"
 #include "state.h"
 void FAIL(char *err)
 {
 	state_done();
 	fprintf(stderr, "ERROR: %s\nExiting...\n", err);
 	exit(EXIT_FAILURE);
 }
 // read m68k memory
 uint32_t m68k_read_memory_32(uint32_t address)
 {
 	uint32_t data = 0xFFFFFFFF;
 	// If ROMLMAP is set, force system to access ROM
 	if (!state.romlmap)
 		address |= 0x800000;
 	if ((address >= 0x800000) && (address <= 0xBFFFFF)) {
 		// ROM access
 		data = (((uint32_t)state.rom[(address + 0) & (ROM_SIZE - 1)] << 24) |
 				((uint32_t)state.rom[(address + 1) & (ROM_SIZE - 1)] << 16) |
 				((uint32_t)state.rom[(address + 2) & (ROM_SIZE - 1)] << 8)  |
 				((uint32_t)state.rom[(address + 3) & (ROM_SIZE - 1)]));
 	} else if (address < state.ram_size - 1) {
 		// RAM
 		data = (((uint32_t)state.ram[address + 0] << 24) |
 				((uint32_t)state.ram[address + 1] << 16) |
 				((uint32_t)state.ram[address + 2] << 8)  |
 				((uint32_t)state.ram[address + 3]));
 	} else if ((address >= 0x420000) && (address <= 0x427FFF)) {
 		// VRAM
 		data = (((uint32_t)state.vram[(address + 0) & 0x7fff] << 24) |
 				((uint32_t)state.vram[(address + 1) & 0x7fff] << 16) |
 				((uint32_t)state.vram[(address + 2) & 0x7fff] << 8)  |
 				((uint32_t)state.vram[(address + 3) & 0x7fff]));
 	} else {
 		// I/O register -- TODO
 		printf("RD32 0x%08X [unknown I/O register]\n", address);
 	}
 	return data;
 }
 uint32_t m68k_read_memory_16(uint32_t address)
 {
 	uint16_t data = 0xFFFF;
 	// If ROMLMAP is set, force system to access ROM
 	if (!state.romlmap)
 		address |= 0x800000;
 	if ((address >= 0x800000) && (address <= 0xBFFFFF)) {
 		// ROM access
 		data = ((state.rom[(address + 0) & (ROM_SIZE - 1)] << 8) |
 				(state.rom[(address + 1) & (ROM_SIZE - 1)]));
 	} else if (address < state.ram_size - 1) {
 		// RAM
 		data = ((state.ram[address + 0] << 8) |
 				(state.ram[address + 1]));
 	} else if ((address >= 0x420000) && (address <= 0x427FFF)) {
 		// VRAM
 		data = (((uint16_t)state.vram[(address + 0) & 0x7fff] << 8)  |
 				((uint16_t)state.vram[(address + 1) & 0x7fff]));
 	} else {
 		// I/O register -- TODO
 		printf("RD16 0x%08X [unknown I/O register]\n", address);
 	}
 	return data;
 }
 uint32_t m68k_read_memory_8(uint32_t address)
 {
 	uint8_t data = 0xFF;
 	// If ROMLMAP is set, force system to access ROM
 	if (!state.romlmap)
 		address |= 0x800000;
 	if ((address >= 0x800000) && (address <= 0xBFFFFF)) {
 		// ROM access
 		data = state.rom[(address + 0) & (ROM_SIZE - 1)];
 	} else if (address < state.ram_size) {
 		// RAM access
 		data = state.ram[address + 0];
 	} else if ((address >= 0x420000) && (address <= 0x427FFF)) {
 		// VRAM
 		data = state.vram[(address + 0) & 0x7fff];
 	} else {
 		// I/O register -- TODO
 		printf("RD08 0x%08X [unknown I/O register]\n", address);
 	}
 	return data;
 }
 // write m68k memory
 void m68k_write_memory_32(uint32_t address, uint32_t value)
 {
 	// If ROMLMAP is set, force system to access ROM
 	if (!state.romlmap)
 		address |= 0x800000;
 	if ((address >= 0x800000) && (address <= 0xBFFFFF)) {
 		// ROM access
 		// TODO: bus error here? can't write to rom!
 	} else if (address < state.ram_size) {
 		// RAM access
 		state.ram[address + 0] = (value >> 24) & 0xff;
 		state.ram[address + 1] = (value >> 16) & 0xff;
 		state.ram[address + 2] = (value >> 8)  & 0xff;
 		state.ram[address + 3] =  value        & 0xff;
 	} else if ((address >= 0x420000) && (address <= 0x427FFF)) {
 		// VRAM access
 		state.vram[(address + 0) & 0x7fff] = (value >> 24) & 0xff;
 		state.vram[(address + 1) & 0x7fff] = (value >> 16) & 0xff;
 		state.vram[(address + 2) & 0x7fff] = (value >> 8)  & 0xff;
 		state.vram[(address + 3) & 0x7fff] =  value        & 0xff;
 	} else {
 		switch (address) {
 			case 0xE43000:	state.romlmap = ((value & 0x8000) == 0x8000); break;	// GCR3: ROMLMAP
 			default:		printf("WR32 0x%08X ==> 0x%08X\n", address, value); break;
 		}
 	}
 }
 void m68k_write_memory_16(uint32_t address, uint32_t value)
 {
 	// If ROMLMAP is set, force system to access ROM
 	if (!state.romlmap)
 		address |= 0x800000;
 	if ((address >= 0x800000) && (address <= 0xBFFFFF)) {
 		// ROM access
 		// TODO: bus error here? can't write to rom!
 	} else if (address < state.ram_size) {
 		// RAM access
 		state.ram[address + 0] = (value >> 8)  & 0xff;
 		state.ram[address + 1] =  value        & 0xff;
 	} else if ((address >= 0x420000) && (address <= 0x427FFF)) {
 		// VRAM access
 		state.vram[(address + 0) & 0x7fff] = (value >> 8) & 0xff;
 		state.vram[(address + 1) & 0x7fff] =  value       & 0xff;
 	} else {
 		switch (address) {
 			case 0xE43000:	state.romlmap = ((value & 0x8000) == 0x8000); break;	// GCR3: ROMLMAP
 			default:		printf("WR16 0x%08X ==> 0x%04X\n", address, value); break;
 		}
 	}
 }
 void m68k_write_memory_8(uint32_t address, uint32_t value)
 {
 	// If ROMLMAP is set, force system to access ROM
 	if (!state.romlmap)
 		address |= 0x800000;
 	if ((address >= 0x800000) && (address <= 0xBFFFFF)) {
 		// ROM access
 		// TODO: bus error here? can't write to rom!
 	} else if (address < state.ram_size) {
 		state.ram[address] = value & 0xff;
 	} else if ((address >= 0x420000) && (address <= 0x427FFF)) {
 		// VRAM access
 		state.vram[address & 0x7fff] = value;
 	} else {
 		switch (address) {
 			case 0xE43000:	state.romlmap = ((value & 0x80) == 0x80); break;	// GCR3: ROMLMAP
 			default:		printf("WR08 0x%08X ==> 0x%02X\n", address, value); break;
 		}
 	}
 }
 // for the disassembler
 uint32_t m68k_read_disassembler_32(uint32_t addr) { return m68k_read_memory_32(addr); }
 uint32_t m68k_read_disassembler_16(uint32_t addr) { return m68k_read_memory_16(addr); }
 uint32_t m68k_read_disassembler_8 (uint32_t addr) { return m68k_read_memory_8 (addr); }
 int main(void)
 {
 	// copyright banner
 	printf("FreeBee: A Quick-and-Dirty AT&T 3B1 Emulator. Version %s, %s mode.\n", VER_FULLSTR, VER_BUILD_TYPE);
 	printf("Copyright (C) 2010 P. A. Pemberton. All rights reserved.\nLicensed under the Apache License Version 2.0.\n");
 	printf("Musashi M680x0 emulator engine developed by Karl Stenerud <kstenerud@gmail.com>\n");
 	printf("Built %s by %s@%s.\n", VER_COMPILE_DATETIME, VER_COMPILE_BY, VER_COMPILE_HOST);
 	printf("Compiler: %s\n", VER_COMPILER);
 	printf("CFLAGS: %s\n", VER_CFLAGS);
 	printf("\n");
 	// set up system state
 	// 512K of RAM
 	state_init(512*1024);
 	// set up musashi and reset the CPU
 	m68k_set_cpu_type(M68K_CPU_TYPE_68010);
 	m68k_pulse_reset();
 /*
 	size_t i = 0x80001a;
 	size_t len;
 	do {
 		char dasm[512];
 		len = m68k_disassemble(dasm, i, M68K_CPU_TYPE_68010);
 		printf("%06X: %s\n", i, dasm);
 		i += len;
 	} while (i < 0x8000ff);
 */
 	// set up SDL
 	if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER) == -1) {
 		printf("Could not initialise SDL: %s.\n", SDL_GetError());
 		return -1;
 	}
 	/***
 	 * The 3B1 CPU runs at 10MHz, with DMA running at 1MHz and video refreshing at
 	 * around 60Hz (???), with a 60Hz periodic interrupt.
 	 */
 	const uint32_t TIMESLOT_FREQUENCY = 240;	// Hz
 	const uint32_t MILLISECS_PER_TIMESLOT = 1e3 / TIMESLOT_FREQUENCY;
 	const uint32_t CLOCKS_PER_60HZ = (10e6 / 60);
 	uint32_t next_timeslot = SDL_GetTicks() + MILLISECS_PER_TIMESLOT;
 	uint32_t clock_cycles = 0;
 	bool exitEmu = false;
 	for (;;) {
 		// Run the CPU for however many cycles we need to. CPU core clock is
 		// 10MHz, and we're running at 240Hz/timeslot. Thus: 10e6/240 or
 		// 41667 cycles per timeslot.
 		clock_cycles += m68k_execute(10e6/TIMESLOT_FREQUENCY);
 		// TODO: run DMA here
 		// Is it time to run the 60Hz periodic interrupt yet?
 		if (clock_cycles > CLOCKS_PER_60HZ) {
 			// TODO: refresh screen
 			// TODO: trigger periodic interrupt (if enabled)
 			// decrement clock cycle counter, we've handled the intr.
 			clock_cycles -= CLOCKS_PER_60HZ;
 		}
 		// make sure frame rate is equal to real time
 		uint32_t now = SDL_GetTicks();
 		if (now < next_timeslot) {
 			// timeslot finished early -- eat up some time
 			SDL_Delay(next_timeslot - now);
 		} else {
 			// timeslot finished late -- skip ahead to gain time
 			// TODO: if this happens a lot, we should let the user know
 			// that their PC might not be fast enough...
 			next_timeslot = now;
 		}
 		// advance to the next timeslot
 		next_timeslot += MILLISECS_PER_TIMESLOT;
 		// if we've been asked to exit the emulator, then do so.
 		if (exitEmu) break;
 	}
 	// shut down and exit
 	SDL_Quit();
 	return 0;
 }

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src/main.c@724d2f6deb37 (annotated)

src/main.c