src/main.c

Mon, 06 Dec 2010 08:27:21 +0000

author
Philip Pemberton <philpem@philpem.me.uk>
date
Mon, 06 Dec 2010 08:27:21 +0000
changeset 76
2ef98ea1e944
parent 53
e1693c4b8a0c
child 77
e7898cbae0c6
child 78
c149c13aff1c
permissions
-rw-r--r--

move edge-sensitive FDC IRQ to main()

     1 #include <stdio.h>
     2 #include <stdlib.h>
     3 #include <stdint.h>
     4 #include <stdbool.h>
     5 #include <malloc.h>
     6 #include <string.h>
     8 #include "SDL.h"
    10 #include "musashi/m68k.h"
    11 #include "version.h"
    12 #include "state.h"
    13 #include "memory.h"
    15 void FAIL(char *err)
    16 {
    17 	state_done();
    18 	fprintf(stderr, "ERROR: %s\nExiting...\n", err);
    19 	exit(EXIT_FAILURE);
    20 }
    22 /**
    23  * @brief Set the pixel at (x, y) to the given value
    24  * @note The surface must be locked before calling this!
    25  * @param	surface		SDL surface upon which to draw
    26  * @param	x			X co-ordinate
    27  * @param	y			Y co-ordinate
    28  * @param	pixel		Pixel value (from SDL_MapRGB)
    29  */
    30 void putpixel(SDL_Surface *surface, int x, int y, Uint32 pixel)
    31 {
    32 	int bpp = surface->format->BytesPerPixel;
    33 	/* Here p is the address to the pixel we want to set */
    34 	Uint8 *p = (Uint8 *)surface->pixels + y * surface->pitch + x * bpp;
    36 	switch (bpp) {
    37 		case 1:
    38 			*p = pixel;
    39 			break;
    41 		case 2:
    42 			*(Uint16 *)p = pixel;
    43 			break;
    45 		case 3:
    46 			if (SDL_BYTEORDER == SDL_BIG_ENDIAN) {
    47 				p[0] = (pixel >> 16) & 0xff;
    48 				p[1] = (pixel >> 8) & 0xff;
    49 				p[2] = pixel & 0xff;
    50 			}
    51 			else {
    52 				p[0] = pixel & 0xff;
    53 				p[1] = (pixel >> 8) & 0xff;
    54 				p[2] = (pixel >> 16) & 0xff;
    55 			}
    56 			break;
    58 		case 4:
    59 			*(Uint32 *)p = pixel;
    60 			break;
    62 		default:
    63 			break;           /* shouldn't happen, but avoids warnings */
    64 	} // switch
    65 }
    68 /**
    69  * @brief	Refresh the screen.
    70  * @param	surface		SDL surface upon which to draw.
    71  */
    72 void refreshScreen(SDL_Surface *s)
    73 {
    74 	// Lock the screen surface (if necessary)
    75 	if (SDL_MUSTLOCK(s)) {
    76 		if (SDL_LockSurface(s) < 0) {
    77 			fprintf(stderr, "ERROR: Unable to lock screen!\n");
    78 			exit(EXIT_FAILURE);
    79 		}
    80 	}
    82 	// Map the foreground and background colours
    83 	Uint32 fg = SDL_MapRGB(s->format, 0x00, 0xFF, 0x00);	// green foreground
    84 //	Uint32 fg = SDL_MapRGB(s->format, 0xFF, 0xC1, 0x06);	// amber foreground
    85 //	Uint32 fg = SDL_MapRGB(s->format, 0xFF, 0xFF, 0xFF);	// white foreground
    86 	Uint32 bg = SDL_MapRGB(s->format, 0x00, 0x00, 0x00);	// black background
    88 	// Refresh the 3B1 screen area first. TODO: only do this if VRAM has actually changed!
    89 	uint32_t vram_address = 0;
    90 	for (int y=0; y<348; y++) {
    91 		for (int x=0; x<720; x+=16) {	// 720 pixels, monochrome, packed into 16bit words
    92 			// Get the pixel
    93 			uint16_t val = RD16(state.vram, vram_address, sizeof(state.vram)-1);
    94 			vram_address += 2;
    95 			// Now copy it to the video buffer
    96 			for (int px=0; px<16; px++) {
    97 				if (val & 1)
    98 					putpixel(s, x+px, y, fg);
    99 				else
   100 					putpixel(s, x+px, y, bg);
   101 				val >>= 1;
   102 			}
   103 		}
   104 	}
   106 	// TODO: blit LEDs and status info
   108 	// Unlock the screen surface
   109 	if (SDL_MUSTLOCK(s)) {
   110 		SDL_UnlockSurface(s);
   111 	}
   113 	// Trigger a refresh -- TODO: partial refresh depending on whether we
   114 	// refreshed the screen area, status area, both, or none. Use SDL_UpdateRect() for this.
   115 	SDL_Flip(s);
   116 }
   118 /**
   119  * @brief	Handle events posted by SDL.
   120  */
   121 bool HandleSDLEvents(SDL_Surface *screen)
   122 {
   123 	SDL_Event event;
   124 	while (SDL_PollEvent(&event))
   125 	{
   126 		switch (event.type) {
   127 			case SDL_QUIT:
   128 				// Quit button tagged. Exit.
   129 				return true;
   130 			case SDL_KEYDOWN:
   131 				switch (event.key.keysym.sym) {
   132 					case SDLK_F12:
   133 						if (event.key.keysym.mod & (KMOD_LALT | KMOD_RALT))
   134 							// ALT-F12 pressed; exit emulator
   135 							return true;
   136 						break;
   137 					default:
   138 						break;
   139 				}
   140 				break;
   141 			default:
   142 				break;
   143 		}
   144 	}
   146 	return false;
   147 }
   150 /****************************
   151  * blessed be thy main()...
   152  ****************************/
   154 int main(void)
   155 {
   156 	// copyright banner
   157 	printf("FreeBee: A Quick-and-Dirty AT&T 3B1 Emulator. Version %s, %s mode.\n", VER_FULLSTR, VER_BUILD_TYPE);
   158 	printf("Copyright (C) 2010 P. A. Pemberton. All rights reserved.\nLicensed under the Apache License Version 2.0.\n");
   159 	printf("Musashi M680x0 emulator engine developed by Karl Stenerud <kstenerud@gmail.com>\n");
   160 	printf("Built %s by %s@%s.\n", VER_COMPILE_DATETIME, VER_COMPILE_BY, VER_COMPILE_HOST);
   161 	printf("Compiler: %s\n", VER_COMPILER);
   162 	printf("CFLAGS: %s\n", VER_CFLAGS);
   163 	printf("\n");
   165 	// set up system state
   166 	// 512K of RAM
   167 	state_init(512*1024);
   169 	// set up musashi and reset the CPU
   170 	m68k_set_cpu_type(M68K_CPU_TYPE_68010);
   171 	m68k_pulse_reset();
   173 	// Set up SDL
   174 	if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER) == -1) {
   175 		printf("Could not initialise SDL: %s.\n", SDL_GetError());
   176 		exit(EXIT_FAILURE);
   177 	}
   179 	// Make sure SDL cleans up after itself
   180 	atexit(SDL_Quit);
   182 	// Set up the video display
   183 	SDL_Surface *screen = NULL;
   184 	if ((screen = SDL_SetVideoMode(720, 384, 8, SDL_SWSURFACE | SDL_ANYFORMAT)) == NULL) {
   185 		printf("Could not find a suitable video mode: %s.\n", SDL_GetError());
   186 		exit(EXIT_FAILURE);
   187 	}
   188 	printf("Set %dx%d at %d bits-per-pixel mode\n\n", screen->w, screen->h, screen->format->BitsPerPixel);
   189 	SDL_WM_SetCaption("FreeBee 3B1 emulator", "FreeBee");
   191 	// Load a disc image
   192 	FILE *disc = fopen("discim", "rb");
   193 	wd2797_load(&state.fdc_ctx, disc, 512, 10, 2);
   195 	/***
   196 	 * The 3B1 CPU runs at 10MHz, with DMA running at 1MHz and video refreshing at
   197 	 * around 60Hz (???), with a 60Hz periodic interrupt.
   198 	 */
   199 	const uint32_t TIMESLOT_FREQUENCY = 1000;//240;	// Hz
   200 	const uint32_t MILLISECS_PER_TIMESLOT = 1e3 / TIMESLOT_FREQUENCY;
   201 	const uint32_t CLOCKS_PER_60HZ = (10e6 / 60);
   202 	uint32_t next_timeslot = SDL_GetTicks() + MILLISECS_PER_TIMESLOT;
   203 	uint32_t clock_cycles = 0;
   204 	bool exitEmu = false;
   205 	bool lastirq_fdc = false;
   206 	for (;;) {
   207 		// Run the CPU for however many cycles we need to. CPU core clock is
   208 		// 10MHz, and we're running at 240Hz/timeslot. Thus: 10e6/240 or
   209 		// 41667 cycles per timeslot.
   210 		clock_cycles += m68k_execute(10e6/TIMESLOT_FREQUENCY);
   212 		// Run the DMA engine
   213 		if (state.dmaen) {
   214 			printf("DMA: copy addr=%08X count=%08X idmarw=%d dmarw=%d\n", state.dma_address, state.dma_count, state.idmarw, state.dma_reading);
   215 			if (state.dmaenb) {
   216 				state.dmaenb = false;
   217 				state.dma_count++;
   218 			}
   219 			// DMA ready to go -- so do it.
   220 			size_t num = 0;
   221 			while (state.dma_count < 0x4000) {
   222 				uint16_t d = 0;
   224 				// num tells us how many words we've copied. If this is greater than the per-timeslot DMA maximum, bail out!
   225 				if (num > (1e6/TIMESLOT_FREQUENCY)) break;
   227 				// Evidently we have more words to copy. Copy them.
   228 				if (!wd2797_get_drq(&state.fdc_ctx)) {
   229 //					printf("\tDMABAIL: no data! dmac=%04X dmaa=%04X\n", state.dma_count, state.dma_address);
   230 					// Bail out, no data available. Try again later.
   231 					// TODO: handle HDD controller too
   232 					break;
   233 				}
   235 				if (!state.dma_reading) {
   236 					// Data available. Get it from the FDC.
   237 					d = wd2797_read_reg(&state.fdc_ctx, WD2797_REG_DATA);
   238 					d <<= 8;
   239 					d += wd2797_read_reg(&state.fdc_ctx, WD2797_REG_DATA);
   241 					// TODO: FIXME: if we get a pagefault, it NEEDS to be tagged as 'peripheral sourced'... this is a HACK!
   242 					m68k_write_memory_16(state.dma_address << 1, d);
   243 				} else {
   244 					// Data write to FDC
   245 					// TODO: FIXME: if we get a pagefault, it NEEDS to be tagged as 'peripheral sourced'... this is a HACK!
   246 					d = m68k_read_memory_16(state.dma_address << 1);
   248 					wd2797_write_reg(&state.fdc_ctx, WD2797_REG_DATA, (d >> 8));
   249 					wd2797_write_reg(&state.fdc_ctx, WD2797_REG_DATA, (d & 0xff));
   250 				}
   252 				// Increment DMA address
   253 				state.dma_address++;
   254 				// Increment number of words transferred
   255 				num++; state.dma_count++;
   256 			}
   258 			// Turn off DMA engine if we finished this cycle
   259 			if (state.dma_count >= 0x4000) {
   260 //				printf("\tDMATRAN: transfer complete! dmaa=%06X, dmac=%04X\n", state.dma_address, state.dma_count);
   261 				state.dma_count = 0;
   262 				state.dmaen = false;
   263 			}
   264 		}
   266 		// Any interrupts?
   267 		if (!lastirq_fdc) {
   268 			if (wd2797_get_irq(&state.fdc_ctx)) {
   269 				lastirq_fdc = true;
   270 				m68k_set_irq(2);
   271 			} else {
   272 				lastirq_fdc = false;
   273 			}
   274 		} else {
   275 			m68k_set_irq(0);
   276 		}
   278 		// Is it time to run the 60Hz periodic interrupt yet?
   279 		if (clock_cycles > CLOCKS_PER_60HZ) {
   280 			// Refresh the screen
   281 			refreshScreen(screen);
   282 			// TODO: trigger periodic interrupt (if enabled)
   283 			// decrement clock cycle counter, we've handled the intr.
   284 			clock_cycles -= CLOCKS_PER_60HZ;
   285 		}
   287 		// handle SDL events -- returns true if we need to exit
   288 		if (HandleSDLEvents(screen))
   289 			exitEmu = true;
   291 		// make sure frame rate is equal to real time
   292 		uint32_t now = SDL_GetTicks();
   293 		if (now < next_timeslot) {
   294 			// timeslot finished early -- eat up some time
   295 			SDL_Delay(next_timeslot - now);
   296 		} else {
   297 			// timeslot finished late -- skip ahead to gain time
   298 			// TODO: if this happens a lot, we should let the user know
   299 			// that their PC might not be fast enough...
   300 			next_timeslot = now;
   301 		}
   302 		// advance to the next timeslot
   303 		next_timeslot += MILLISECS_PER_TIMESLOT;
   305 		// if we've been asked to exit the emulator, then do so.
   306 		if (exitEmu) break;
   307 	}
   309 	// Release the disc image
   310 	wd2797_unload(&state.fdc_ctx);
   311 	fclose(disc);
   313 	return 0;
   314 }