src/main.c

Sun, 05 Dec 2010 16:20:00 +0000

author
Philip Pemberton <philpem@philpem.me.uk>
date
Sun, 05 Dec 2010 16:20:00 +0000
changeset 52
a350dfa92895
parent 50
c3ed7639e32d
child 53
e1693c4b8a0c
permissions
-rw-r--r--

add preliminary WD279x emulation to core

philpem@0 1 #include <stdio.h>
philpem@7 2 #include <stdlib.h>
philpem@4 3 #include <stdint.h>
philpem@7 4 #include <stdbool.h>
philpem@7 5 #include <malloc.h>
philpem@7 6 #include <string.h>
philpem@18 7
philpem@20 8 #include "SDL.h"
philpem@20 9
philpem@4 10 #include "musashi/m68k.h"
philpem@7 11 #include "version.h"
philpem@18 12 #include "state.h"
philpem@40 13 #include "memory.h"
philpem@7 14
philpem@7 15 void FAIL(char *err)
philpem@7 16 {
philpem@7 17 state_done();
philpem@7 18 fprintf(stderr, "ERROR: %s\nExiting...\n", err);
philpem@7 19 exit(EXIT_FAILURE);
philpem@7 20 }
philpem@7 21
philpem@41 22 /**
philpem@41 23 * @brief Set the pixel at (x, y) to the given value
philpem@41 24 * @note The surface must be locked before calling this!
philpem@41 25 * @param surface SDL surface upon which to draw
philpem@41 26 * @param x X co-ordinate
philpem@41 27 * @param y Y co-ordinate
philpem@41 28 * @param pixel Pixel value (from SDL_MapRGB)
philpem@41 29 */
philpem@41 30 void putpixel(SDL_Surface *surface, int x, int y, Uint32 pixel)
philpem@41 31 {
philpem@41 32 int bpp = surface->format->BytesPerPixel;
philpem@41 33 /* Here p is the address to the pixel we want to set */
philpem@41 34 Uint8 *p = (Uint8 *)surface->pixels + y * surface->pitch + x * bpp;
philpem@41 35
philpem@41 36 switch (bpp) {
philpem@41 37 case 1:
philpem@41 38 *p = pixel;
philpem@41 39 break;
philpem@41 40
philpem@41 41 case 2:
philpem@41 42 *(Uint16 *)p = pixel;
philpem@41 43 break;
philpem@41 44
philpem@41 45 case 3:
philpem@41 46 if (SDL_BYTEORDER == SDL_BIG_ENDIAN) {
philpem@41 47 p[0] = (pixel >> 16) & 0xff;
philpem@41 48 p[1] = (pixel >> 8) & 0xff;
philpem@41 49 p[2] = pixel & 0xff;
philpem@41 50 }
philpem@41 51 else {
philpem@41 52 p[0] = pixel & 0xff;
philpem@41 53 p[1] = (pixel >> 8) & 0xff;
philpem@41 54 p[2] = (pixel >> 16) & 0xff;
philpem@41 55 }
philpem@41 56 break;
philpem@41 57
philpem@41 58 case 4:
philpem@41 59 *(Uint32 *)p = pixel;
philpem@41 60 break;
philpem@41 61
philpem@41 62 default:
philpem@41 63 break; /* shouldn't happen, but avoids warnings */
philpem@41 64 } // switch
philpem@41 65 }
philpem@41 66
philpem@41 67
philpem@41 68 /**
philpem@41 69 * @brief Refresh the screen.
philpem@41 70 * @param surface SDL surface upon which to draw.
philpem@41 71 */
philpem@41 72 void refreshScreen(SDL_Surface *s)
philpem@41 73 {
philpem@41 74 // Lock the screen surface (if necessary)
philpem@41 75 if (SDL_MUSTLOCK(s)) {
philpem@41 76 if (SDL_LockSurface(s) < 0) {
philpem@41 77 fprintf(stderr, "ERROR: Unable to lock screen!\n");
philpem@41 78 exit(EXIT_FAILURE);
philpem@41 79 }
philpem@41 80 }
philpem@41 81
philpem@41 82 // Map the foreground and background colours
philpem@42 83 Uint32 fg = SDL_MapRGB(s->format, 0x00, 0xFF, 0x00); // green foreground
philpem@42 84 // Uint32 fg = SDL_MapRGB(s->format, 0xFF, 0xC1, 0x06); // amber foreground
philpem@42 85 // Uint32 fg = SDL_MapRGB(s->format, 0xFF, 0xFF, 0xFF); // white foreground
philpem@42 86 Uint32 bg = SDL_MapRGB(s->format, 0x00, 0x00, 0x00); // black background
philpem@41 87
philpem@41 88 // Refresh the 3B1 screen area first. TODO: only do this if VRAM has actually changed!
philpem@41 89 uint32_t vram_address = 0;
philpem@41 90 for (int y=0; y<348; y++) {
philpem@41 91 for (int x=0; x<720; x+=16) { // 720 pixels, monochrome, packed into 16bit words
philpem@41 92 // Get the pixel
philpem@41 93 uint16_t val = RD16(state.vram, vram_address, sizeof(state.vram)-1);
philpem@41 94 vram_address += 2;
philpem@41 95 // Now copy it to the video buffer
philpem@41 96 for (int px=0; px<16; px++) {
philpem@41 97 if (val & 1)
philpem@41 98 putpixel(s, x+px, y, fg);
philpem@41 99 else
philpem@41 100 putpixel(s, x+px, y, bg);
philpem@45 101 val >>= 1;
philpem@41 102 }
philpem@41 103 }
philpem@41 104 }
philpem@41 105
philpem@41 106 // TODO: blit LEDs and status info
philpem@41 107
philpem@41 108 // Unlock the screen surface
philpem@41 109 if (SDL_MUSTLOCK(s)) {
philpem@41 110 SDL_UnlockSurface(s);
philpem@41 111 }
philpem@41 112
philpem@41 113 // Trigger a refresh -- TODO: partial refresh depending on whether we
philpem@41 114 // refreshed the screen area, status area, both, or none. Use SDL_UpdateRect() for this.
philpem@41 115 SDL_Flip(s);
philpem@41 116 }
philpem@41 117
philpem@47 118 /**
philpem@47 119 * @brief Handle events posted by SDL.
philpem@47 120 */
philpem@47 121 bool HandleSDLEvents(SDL_Surface *screen)
philpem@47 122 {
philpem@47 123 SDL_Event event;
philpem@47 124 while (SDL_PollEvent(&event))
philpem@47 125 {
philpem@47 126 switch (event.type) {
philpem@47 127 case SDL_QUIT:
philpem@47 128 // Quit button tagged. Exit.
philpem@47 129 return true;
philpem@47 130 case SDL_KEYDOWN:
philpem@47 131 switch (event.key.keysym.sym) {
philpem@48 132 case SDLK_F12:
philpem@47 133 if (event.key.keysym.mod & (KMOD_LALT | KMOD_RALT))
philpem@48 134 // ALT-F12 pressed; exit emulator
philpem@47 135 return true;
philpem@47 136 break;
philpem@47 137 default:
philpem@47 138 break;
philpem@47 139 }
philpem@47 140 break;
philpem@47 141 default:
philpem@47 142 break;
philpem@47 143 }
philpem@47 144 }
philpem@47 145
philpem@47 146 return false;
philpem@47 147 }
philpem@47 148
philpem@47 149
philpem@27 150 /****************************
philpem@27 151 * blessed be thy main()...
philpem@27 152 ****************************/
philpem@27 153
philpem@0 154 int main(void)
philpem@0 155 {
philpem@7 156 // copyright banner
philpem@16 157 printf("FreeBee: A Quick-and-Dirty AT&T 3B1 Emulator. Version %s, %s mode.\n", VER_FULLSTR, VER_BUILD_TYPE);
philpem@17 158 printf("Copyright (C) 2010 P. A. Pemberton. All rights reserved.\nLicensed under the Apache License Version 2.0.\n");
philpem@17 159 printf("Musashi M680x0 emulator engine developed by Karl Stenerud <kstenerud@gmail.com>\n");
philpem@16 160 printf("Built %s by %s@%s.\n", VER_COMPILE_DATETIME, VER_COMPILE_BY, VER_COMPILE_HOST);
philpem@16 161 printf("Compiler: %s\n", VER_COMPILER);
philpem@16 162 printf("CFLAGS: %s\n", VER_CFLAGS);
philpem@17 163 printf("\n");
philpem@7 164
philpem@7 165 // set up system state
philpem@7 166 // 512K of RAM
philpem@18 167 state_init(512*1024);
philpem@7 168
philpem@20 169 // set up musashi and reset the CPU
philpem@7 170 m68k_set_cpu_type(M68K_CPU_TYPE_68010);
philpem@7 171 m68k_pulse_reset();
philpem@9 172
philpem@28 173 // Set up SDL
philpem@20 174 if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER) == -1) {
philpem@20 175 printf("Could not initialise SDL: %s.\n", SDL_GetError());
philpem@28 176 exit(EXIT_FAILURE);
philpem@20 177 }
philpem@7 178
philpem@28 179 // Make sure SDL cleans up after itself
philpem@28 180 atexit(SDL_Quit);
philpem@28 181
philpem@28 182 // Set up the video display
philpem@28 183 SDL_Surface *screen = NULL;
philpem@28 184 if ((screen = SDL_SetVideoMode(720, 384, 8, SDL_SWSURFACE | SDL_ANYFORMAT)) == NULL) {
philpem@28 185 printf("Could not find a suitable video mode: %s.\n", SDL_GetError());
philpem@28 186 exit(EXIT_FAILURE);
philpem@28 187 }
philpem@32 188 printf("Set %dx%d at %d bits-per-pixel mode\n\n", screen->w, screen->h, screen->format->BitsPerPixel);
philpem@28 189 SDL_WM_SetCaption("FreeBee 3B1 emulator", "FreeBee");
philpem@28 190
philpem@52 191 // Load a disc image
philpem@52 192 FILE *disc = fopen("discim", "rb");
philpem@52 193 wd2797_load(&state.fdc_ctx, disc, 512, 10, 2);
philpem@52 194
philpem@20 195 /***
philpem@20 196 * The 3B1 CPU runs at 10MHz, with DMA running at 1MHz and video refreshing at
philpem@20 197 * around 60Hz (???), with a 60Hz periodic interrupt.
philpem@20 198 */
philpem@20 199 const uint32_t TIMESLOT_FREQUENCY = 240; // Hz
philpem@20 200 const uint32_t MILLISECS_PER_TIMESLOT = 1e3 / TIMESLOT_FREQUENCY;
philpem@20 201 const uint32_t CLOCKS_PER_60HZ = (10e6 / 60);
philpem@20 202 uint32_t next_timeslot = SDL_GetTicks() + MILLISECS_PER_TIMESLOT;
philpem@20 203 uint32_t clock_cycles = 0;
philpem@16 204 bool exitEmu = false;
philpem@16 205 for (;;) {
philpem@20 206 // Run the CPU for however many cycles we need to. CPU core clock is
philpem@20 207 // 10MHz, and we're running at 240Hz/timeslot. Thus: 10e6/240 or
philpem@20 208 // 41667 cycles per timeslot.
philpem@20 209 clock_cycles += m68k_execute(10e6/TIMESLOT_FREQUENCY);
philpem@20 210
philpem@20 211 // TODO: run DMA here
philpem@16 212
philpem@20 213 // Is it time to run the 60Hz periodic interrupt yet?
philpem@20 214 if (clock_cycles > CLOCKS_PER_60HZ) {
philpem@41 215 // Refresh the screen
philpem@41 216 refreshScreen(screen);
philpem@20 217 // TODO: trigger periodic interrupt (if enabled)
philpem@20 218 // decrement clock cycle counter, we've handled the intr.
philpem@20 219 clock_cycles -= CLOCKS_PER_60HZ;
philpem@16 220 }
philpem@16 221
philpem@47 222 // handle SDL events -- returns true if we need to exit
philpem@47 223 if (HandleSDLEvents(screen))
philpem@47 224 exitEmu = true;
philpem@47 225
philpem@20 226 // make sure frame rate is equal to real time
philpem@20 227 uint32_t now = SDL_GetTicks();
philpem@20 228 if (now < next_timeslot) {
philpem@20 229 // timeslot finished early -- eat up some time
philpem@20 230 SDL_Delay(next_timeslot - now);
philpem@20 231 } else {
philpem@20 232 // timeslot finished late -- skip ahead to gain time
philpem@20 233 // TODO: if this happens a lot, we should let the user know
philpem@20 234 // that their PC might not be fast enough...
philpem@20 235 next_timeslot = now;
philpem@20 236 }
philpem@20 237 // advance to the next timeslot
philpem@20 238 next_timeslot += MILLISECS_PER_TIMESLOT;
philpem@20 239
philpem@20 240 // if we've been asked to exit the emulator, then do so.
philpem@16 241 if (exitEmu) break;
philpem@16 242 }
philpem@7 243
philpem@52 244 // Release the disc image
philpem@52 245 wd2797_unload(&state.fdc_ctx);
philpem@52 246 fclose(disc);
philpem@52 247
philpem@0 248 return 0;
philpem@0 249 }