3b1emu: src/main.c@d61e13d6e2a5 (annotated)

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src/main.c@d61e13d6e2a5 (annotated)

src/main.c

Sat, 19 Apr 2014 02:19:39 -0600

author: andrew@localhost
date: Sat, 19 Apr 2014 02:19:39 -0600
changeset 152: d61e13d6e2a5
parent 134: b826697f411a
permissions: -rw-r--r--

fixed timing on OSes that set a minimum time for sleeps (previously the main loop code assumed no minimum sleep time; the new version uses longer sleeps less frequently)

 #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"
 #include "memory.h"
 void FAIL(char *err)
 {
 	state_done();
 	fprintf(stderr, "ERROR: %s\nExiting...\n", err);
 	exit(EXIT_FAILURE);
 }
 static int load_fd()
 {
 	int writeable = 1;
 	state.fdc_disc = fopen("discim", "r+b");
 	if (!state.fdc_disc){
 		writeable = 0;
 		state.fdc_disc = fopen("discim", "rb");
 	}
 	if (!state.fdc_disc){
 		fprintf(stderr, "ERROR loading disc image 'discim'.\n");
 		state.fdc_disc = NULL;
 		return (0);
 	}else{
 		wd2797_load(&state.fdc_ctx, state.fdc_disc, 512, 10, 2, writeable);
 		fprintf(stderr, "Disc image loaded.\n");
 		return (1);
 	}
 }
 static int load_hd()
 {
 	state.hdc_disc0 = fopen("hd.img", "r+b");
 	if (!state.hdc_disc0){
 		fprintf(stderr, "ERROR loading disc image 'hd.img'.\n");
 		state.hdc_disc0 = NULL;
 		return (0);
 	}else{
 		wd2010_init(&state.hdc_ctx, state.hdc_disc0, 512, 16, 8);
 		fprintf(stderr, "Disc image loaded.\n");
 		return (1);
 	}
 }
 /**
  * @brief Set the pixel at (x, y) to the given value
  * @note The surface must be locked before calling this!
  * @param	surface		SDL surface upon which to draw
  * @param	x			X co-ordinate
  * @param	y			Y co-ordinate
  * @param	pixel		Pixel value (from SDL_MapRGB)
  */
 void putpixel(SDL_Surface *surface, int x, int y, Uint32 pixel)
 {
 	int bpp = surface->format->BytesPerPixel;
 	/* Here p is the address to the pixel we want to set */
 	Uint8 *p = (Uint8 *)surface->pixels + y * surface->pitch + x * bpp;
 	switch (bpp) {
 		case 1:
 			*p = pixel;
 			break;
 		case 2:
 			*(Uint16 *)p = pixel;
 			break;
 		case 3:
 			if (SDL_BYTEORDER == SDL_BIG_ENDIAN) {
 				p[0] = (pixel >> 16) & 0xff;
 				p[1] = (pixel >> 8) & 0xff;
 				p[2] = pixel & 0xff;
 			}
 			else {
 				p[0] = pixel & 0xff;
 				p[1] = (pixel >> 8) & 0xff;
 				p[2] = (pixel >> 16) & 0xff;
 			}
 			break;
 		case 4:
 			*(Uint32 *)p = pixel;
 			break;
 		default:
 			break;           /* shouldn't happen, but avoids warnings */
 	} // switch
 }
 /**
  * @brief	Refresh the screen.
  * @param	surface		SDL surface upon which to draw.
  */
 void refreshScreen(SDL_Surface *s)
 {
 	// Lock the screen surface (if necessary)
 	if (SDL_MUSTLOCK(s)) {
 		if (SDL_LockSurface(s) < 0) {
 			fprintf(stderr, "ERROR: Unable to lock screen!\n");
 			exit(EXIT_FAILURE);
 		}
 	}
 	// Map the foreground and background colours
 	Uint32 fg = SDL_MapRGB(s->format, 0x00, 0xFF, 0x00);	// green foreground
 //	Uint32 fg = SDL_MapRGB(s->format, 0xFF, 0xC1, 0x06);	// amber foreground
 //	Uint32 fg = SDL_MapRGB(s->format, 0xFF, 0xFF, 0xFF);	// white foreground
 	Uint32 bg = SDL_MapRGB(s->format, 0x00, 0x00, 0x00);	// black background
 	// Refresh the 3B1 screen area first. TODO: only do this if VRAM has actually changed!
 	uint32_t vram_address = 0;
 	for (int y=0; y<348; y++) {
 		for (int x=0; x<720; x+=16) {	// 720 pixels, monochrome, packed into 16bit words
 			// Get the pixel
 			uint16_t val = RD16(state.vram, vram_address, sizeof(state.vram)-1);
 			vram_address += 2;
 			// Now copy it to the video buffer
 			for (int px=0; px<16; px++) {
 				if (val & 1)
 					putpixel(s, x+px, y, fg);
 				else
 					putpixel(s, x+px, y, bg);
 				val >>= 1;
 			}
 		}
 	}
 	// TODO: blit LEDs and status info
 	// Unlock the screen surface
 	if (SDL_MUSTLOCK(s)) {
 		SDL_UnlockSurface(s);
 	}
 	// Trigger a refresh -- TODO: partial refresh depending on whether we
 	// refreshed the screen area, status area, both, or none. Use SDL_UpdateRect() for this.
 	SDL_Flip(s);
 }
 /**
  * @brief	Handle events posted by SDL.
  */
 bool HandleSDLEvents(SDL_Surface *screen)
 {
 	SDL_Event event;
 	while (SDL_PollEvent(&event))
 	{
 		if ((event.type == SDL_KEYDOWN) || (event.type == SDL_KEYUP)) {
 			keyboard_event(&state.kbd, &event);
 		}
 		switch (event.type) {
 			case SDL_QUIT:
 				// Quit button tagged. Exit.
 				return true;
 			case SDL_KEYDOWN:
 				switch (event.key.keysym.sym) {
 					case SDLK_F11:
 						if (state.fdc_disc) {
 							wd2797_unload(&state.fdc_ctx);
 							fclose(state.fdc_disc);
 							state.fdc_disc = NULL;
 							fprintf(stderr, "Disc image unloaded.\n");
 						} else {
 							load_fd();
 						}
 						break;
 					case SDLK_F12:
 						if (event.key.keysym.mod & (KMOD_LALT | KMOD_RALT))
 							// ALT-F12 pressed; exit emulator
 							return true;
 						break;
 					default:
 						break;
 				}
 				break;
 			default:
 				break;
 		}
 	}
 	return false;
 }
 /****************************
  * blessed be thy main()...
  ****************************/
 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
 	int i;
 	if ((i = state_init(2048*1024, 2048*1024)) != STATE_E_OK) {
 		fprintf(stderr, "ERROR: Emulator initialisation failed. Error code %d.\n", i);
 		return i;
 	}
 	// set up musashi and reset the CPU
 	m68k_set_cpu_type(M68K_CPU_TYPE_68010);
 	m68k_pulse_reset();
 	// Set up SDL
 	if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER) == -1) {
 		printf("Could not initialise SDL: %s.\n", SDL_GetError());
 		exit(EXIT_FAILURE);
 	}
 	// Make sure SDL cleans up after itself
 	atexit(SDL_Quit);
 	// Set up the video display
 	SDL_Surface *screen = NULL;
 	if ((screen = SDL_SetVideoMode(720, 384, 8, SDL_SWSURFACE | SDL_ANYFORMAT)) == NULL) {
 		printf("Could not find a suitable video mode: %s.\n", SDL_GetError());
 		exit(EXIT_FAILURE);
 	}
 	printf("Set %dx%d at %d bits-per-pixel mode\n\n", screen->w, screen->h, screen->format->BitsPerPixel);
 	SDL_WM_SetCaption("FreeBee 3B1 emulator", "FreeBee");
 	// Load a disc image
 	load_fd();
 	load_hd();
 	/***
 	 * 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 SYSTEM_CLOCK = 10e6; // Hz
 	const uint32_t TIMESLOT_FREQUENCY = 100;//240;	// Hz
 	const uint32_t MILLISECS_PER_TIMESLOT = 1e3 / TIMESLOT_FREQUENCY;
 	const uint32_t CLOCKS_PER_60HZ = (SYSTEM_CLOCK / 60);
 	const uint32_t NUM_CPU_TIMESLOTS = 500;
 	uint32_t next_timeslot = SDL_GetTicks() + MILLISECS_PER_TIMESLOT;
 	uint32_t clock_cycles = 0, tmp;
 	bool exitEmu = false;
 	/*bool lastirq_fdc = false;*/
 	for (;;) {
 		for (i = 0; i < NUM_CPU_TIMESLOTS; i++){
 			// 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.
 			tmp = m68k_execute(SYSTEM_CLOCK/TIMESLOT_FREQUENCY / NUM_CPU_TIMESLOTS);
 			clock_cycles += tmp;
 			// Run the DMA engine
 			if (state.dmaen) {
 				// DMA ready to go -- so do it.
 				size_t num = 0;
 				while (state.dma_count < 0x4000) {
 					uint16_t d = 0;
 					// num tells us how many words we've copied. If this is greater than the per-timeslot DMA maximum, bail out!
 					if (num > (1e6/TIMESLOT_FREQUENCY)) break;
 					// Evidently we have more words to copy. Copy them.
 					if (state.fd_selected){
 						if (!wd2797_get_drq(&state.fdc_ctx)) {
 							// Bail out, no data available. Try again later.
 							break;
 						}
 					}else if (state.hd_selected){
 						if (!wd2010_get_drq(&state.hdc_ctx)) {
 							// Bail out, no data available. Try again later.
 							break;
 						}
 					}else{
 						printf("ERROR: DMA attempt with no drive selected!\n");
 					}
 					if (!access_check_dma(state.dma_reading)) {
 						break;
 					}
 					uint32_t newAddr;
 					// Map logical address to a physical RAM address
 					newAddr = mapAddr(state.dma_address, !state.dma_reading);
 					if (!state.dma_reading) {
 						// Data available. Get it from the FDC or HDC.
 						if (state.fd_selected) {
 							d = wd2797_read_reg(&state.fdc_ctx, WD2797_REG_DATA);
 							d <<= 8;
 							d += wd2797_read_reg(&state.fdc_ctx, WD2797_REG_DATA);
 						}else if (state.hd_selected) {
 							d = wd2010_read_data(&state.hdc_ctx);
 							d <<= 8;
 							d += wd2010_read_data(&state.hdc_ctx);
 						}
 						if (newAddr <= 0x1FFFFF) {
 							WR16(state.base_ram, newAddr, state.base_ram_size - 1, d);
 						} else if (newAddr >= 0x200000) {
 							WR16(state.exp_ram, newAddr - 0x200000, state.exp_ram_size - 1, d);
 						}
 					} else {
 						// Data write to FDC or HDC.
 						// Get the data from RAM
 						if (newAddr <= 0x1fffff) {
 							d = RD16(state.base_ram, newAddr, state.base_ram_size - 1);
 						} else {
 							if (newAddr <= (state.exp_ram_size + 0x200000 - 1))
 								d = RD16(state.exp_ram, newAddr - 0x200000, state.exp_ram_size - 1);
 							else
 								d = 0xffff;
 						}
 						// Send the data to the FDD or HDD
 						if (state.fd_selected){
 							wd2797_write_reg(&state.fdc_ctx, WD2797_REG_DATA, (d >> 8));
 							wd2797_write_reg(&state.fdc_ctx, WD2797_REG_DATA, (d & 0xff));
 						}else if (state.hd_selected){
 							wd2010_write_data(&state.hdc_ctx, (d >> 8));
 							wd2010_write_data(&state.hdc_ctx, (d & 0xff));
 						}
 					}
 					// Increment DMA address
 					state.dma_address+=2;
 					// Increment number of words transferred
 					num++; state.dma_count++;
 				}
 				// Turn off DMA engine if we finished this cycle
 				if (state.dma_count >= 0x4000) {
 					// FIXME? apparently this isn't required... or is it?
 					state.dma_count = 0x3fff;
 					/*state.dmaen = false;*/
 				}
 			}else if (wd2010_get_drq(&state.hdc_ctx)){
 				wd2010_dma_miss(&state.hdc_ctx);
 			}else if (wd2797_get_drq(&state.fdc_ctx)){
 				wd2797_dma_miss(&state.fdc_ctx);
 			}
 			// Any interrupts? --> TODO: masking
 /*			if (!lastirq_fdc) {
 				if (wd2797_get_irq(&state.fdc_ctx)) {
 					lastirq_fdc = true;
 					m68k_set_irq(2);
 				}
 			}
 */
 			if (wd2797_get_irq(&state.fdc_ctx) || wd2010_get_irq(&state.hdc_ctx)) {
 				m68k_set_irq(2);
 			}else if (keyboard_get_irq(&state.kbd)) {
 				m68k_set_irq(3);
 			} else {
 //				if (!state.timer_asserted){
 					m68k_set_irq(0);
 //				}
 			}
 		}
 		// Is it time to run the 60Hz periodic interrupt yet?
 		if (clock_cycles > CLOCKS_PER_60HZ) {
 			// Refresh the screen
 			refreshScreen(screen);
 			if (state.timer_enabled){
 				m68k_set_irq(6);
 				state.timer_asserted = true;
 			}
 			// scan the keyboard
 			keyboard_scan(&state.kbd);
 			// decrement clock cycle counter, we've handled the intr.
 			clock_cycles -= CLOCKS_PER_60HZ;
 		}
 		// handle SDL events -- returns true if we need to exit
 		if (HandleSDLEvents(screen))
 			exitEmu = true;
 		// 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;
 	}
 	// Release the disc image
 	wd2797_unload(&state.fdc_ctx);
 	fclose(state.fdc_disc);
 	return 0;
 }

3b1emu / annotate

src/main.c@d61e13d6e2a5 (annotated)

src/main.c