Parse binjgb.ini file

Has very simple format, with following keys:

```
autoload=filename.gb
audio-frequency=44100
audio-frames=2048
builtin-palette=0
force-dmg=0
rewind-frames-per-base-state=45
rewind-buffer-capacity-megabytes=32
rewind-scale=1.5
render-scale=4
random-seed=0
sgb-border=0
```

Some of these probably should not be adjusted by users. :-)

README.md

@@ -168,6 +168,64 @@ Keys:
 | Pause | <kbd>Space</kbd> |
 | Step one frame | <kbd>N</kbd> |
 
+## INI file
+
+Binjgb tries to read from `binjgb.ini` on startup for configuration. The
+following keys are supported:
+
+```
+# Load this file automatically on startup
+autoload=filename.gb
+
+# Set the audio frequency in Hz
+audio-frequency=44100
+
+# Set the number of audio frames per buffer
+# lower=better latency, more pops/clicks
+# higher=worse latency, fewer pops/clicks
+audio-frames=2048
+
+# Set to the index of a builtin palette
+# (valid numbers are 0..82)
+builtin-palette=0
+
+# Force the emulator to run in DMG (original gameboy) mode.
+# 0=Don't force DMG
+# 1=Force DMG
+force-dmg=0
+
+# The number of video frames to display before storing a full dump of
+# the emulator state in the rewind buffer. Probably best to leave this
+# alone
+rewind-frames-per-base-state=45
+
+# The number of megabytes to allocate to the rewind buffer.
+# lower=less memory usage, less rewind time
+# higher=more memory usage, more rewind time
+rewind-buffer-capacity-megabytes=32
+
+# The speed at which to rewind the game, as a scale.
+# 1=rewind at 1x
+# 2=rewind at 2x
+# etc.
+rewind-scale=1.5
+
+# How much to scale the emulator window at startup.
+render-scale=4
+
+# What to set the random seed to when initializing memory. Using 0
+# disables memory randomization.
+random-seed=0
+
+# Whether to display the SGB border or not.
+# 0=Don't display SGB border
+# 1=Display SGB border, even if it doesn't exist.
+sgb-border=0
+```
+
+The INI file is loaded before parsing the command line flags, so you can use
+the command line to override the values in the INI file.
+
 ## Running tests
 
 Run `scripts/build_tests.py` to download and build the necessary testsuites.

src/binjgb.c

@@ -26,13 +26,6 @@
 #define STATUS_TEXT_RGBA MAKE_RGBA(255, 0, 0, 255)
 #define STATUS_TEXT_TIMEOUT 120 /* Frames */
 
-// TODO: make these configurable?
-#define AUDIO_FREQUENCY 44100
-#define AUDIO_FRAMES 2048 /* ~46ms of latency at 44.1kHz */
-#define REWIND_FRAMES_PER_BASE_STATE 45
-#define REWIND_BUFFER_CAPACITY MEGABYTES(32)
-#define REWIND_CYCLES_PER_FRAME (70224 * 3 / 2) /* Rewind at 1.5x */
-
 typedef enum Layer {
   LAYER_BG,
   LAYER_WINDOW,
@@ -69,6 +62,12 @@ static Bool s_force_dmg;
 static Bool s_use_sgb_border;
 static u32 s_render_scale = 4;
 
+static u32 s_audio_frequency = 44100;
+static u32 s_audio_frames = 2048; /* ~46ms of latency at 44.1kHz */
+static u32 s_rewind_frames_per_base_state = 45;
+static u32 s_rewind_buffer_capacity_megabytes = 32;
+static f32 s_rewind_scale = 1.5f;
+
 static Overlay s_overlay;
 static StatusText s_status_text;
 
@@ -413,9 +412,68 @@ void parse_arguments(int argc, char** argv) {
   exit(1);
 }
 
+void read_ini_file(void) {
+  FILE* file = fopen("binjgb.ini", "r");
+  if (!file) {
+    return;
+  }
+  while (1) {
+    char buffer[1024], *value, *equals, *newline;
+    if (!fgets(buffer, sizeof(buffer), file)) {
+      break;
+    }
+
+    if (buffer[0] == '#' || buffer[0] == '\n') {
+      continue;
+    }
+
+    equals = strchr(buffer, '=');
+    if (!equals) {
+      fprintf(stderr, "warning: bad ini line: %s\n", buffer);
+      continue;
+    }
+    *equals = 0;
+    value = equals + 1;
+
+    newline = strchr(value, '\n');
+    if (newline) {
+      *newline = 0;
+    }
+
+    if (strcmp(buffer, "autoload") == 0) {
+      s_rom_filename = xstrdup(value);
+    } else if (strcmp(buffer, "audio-frequency") == 0) {
+      s_audio_frequency = atoi(value);
+    } else if (strcmp(buffer, "audio-frames") == 0) {
+      s_audio_frames = atoi(value);
+    } else if (strcmp(buffer, "builtin-palette") == 0) {
+      s_builtin_palette = atoi(value);
+    } else if (strcmp(buffer, "force-dmg") == 0) {
+      s_force_dmg = atoi(value);
+    } else if (strcmp(buffer, "rewind-frames-per-base-state") == 0) {
+      s_rewind_frames_per_base_state = atoi(value);
+    } else if (strcmp(buffer, "rewind-buffer-capacity-megabytes") == 0) {
+      s_rewind_buffer_capacity_megabytes = atoi(value);
+    } else if (strcmp(buffer, "rewind-scale") == 0) {
+      s_rewind_scale = atof(value);
+    } else if (strcmp(buffer, "render-scale") == 0) {
+      s_render_scale = atoi(value);
+    } else if (strcmp(buffer, "random-seed") == 0) {
+      s_random_seed = atoi(value);
+    } else if (strcmp(buffer, "sgb-border") == 0) {
+      s_use_sgb_border = atoi(value);
+    } else {
+      fprintf(stderr, "warning: unknown ini key: %s\n", buffer);
+    }
+  }
+  fclose(file);
+}
+
 int main(int argc, char** argv) {
   int result = 1;
 
+  read_ini_file();
+
   parse_arguments(argc, argv);
 
   FileData rom;
@@ -424,8 +482,8 @@ int main(int argc, char** argv) {
   EmulatorInit emulator_init;
   ZERO_MEMORY(emulator_init);
   emulator_init.rom = rom;
-  emulator_init.audio_frequency = AUDIO_FREQUENCY;
-  emulator_init.audio_frames = AUDIO_FRAMES;
+  emulator_init.audio_frequency = s_audio_frequency;
+  emulator_init.audio_frames = s_audio_frames;
   emulator_init.random_seed = s_random_seed;
   emulator_init.builtin_palette = s_builtin_palette;
   emulator_init.force_dmg = s_force_dmg;
@@ -437,11 +495,11 @@ int main(int argc, char** argv) {
   host_init.hooks.key_down = key_down;
   host_init.hooks.key_up = key_up;
   host_init.render_scale = s_render_scale;
-  host_init.audio_frequency = AUDIO_FREQUENCY;
-  host_init.audio_frames = AUDIO_FRAMES;
+  host_init.audio_frequency = s_audio_frequency;
+  host_init.audio_frames = s_audio_frames;
   host_init.audio_volume = s_audio_volume;
-  host_init.rewind.frames_per_base_state = REWIND_FRAMES_PER_BASE_STATE;
-  host_init.rewind.buffer_capacity = REWIND_BUFFER_CAPACITY;
+  host_init.rewind.frames_per_base_state = s_rewind_frames_per_base_state;
+  host_init.rewind.buffer_capacity = s_rewind_buffer_capacity_megabytes * MEGABYTES(1);
   host_init.joypad_filename = s_read_joypad_filename;
   host_init.use_sgb_border = s_use_sgb_border;
   host = host_new(&host_init, e);
@@ -458,7 +516,7 @@ int main(int argc, char** argv) {
   f64 refresh_ms = host_get_monitor_refresh_ms(host);
   while (s_running && host_poll_events(host)) {
     if (s_rewinding) {
-      rewind_by(REWIND_CYCLES_PER_FRAME);
+      rewind_by((Ticks)(PPU_FRAME_TICKS * s_rewind_scale));
     } else if (!s_paused) {
       EmulatorEvent event = host_run_ms(host, refresh_ms);
       if (event & EMULATOR_EVENT_INVALID_OPCODE) {

src/memory.c

@@ -32,4 +32,10 @@ void* xcalloc_(const char* file, int line, size_t count, size_t size) {
   return p;
 }
 
+char* xstrdup_(const char* file, int line, const char* s) {
+  char* p = strdup(s);
+  printf("%s:%d: %s(%p) => %p\n", file, line, __func__, s, p);
+  return p;
+}
+
 #endif

src/memory.h

@@ -8,6 +8,7 @@
 #define BINJGB_MEMORY_H_
 
 #include <stdlib.h>
+#include <string.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -20,17 +21,20 @@ extern "C" {
 #define xmalloc(size) xmalloc_(__FILE__, __LINE__, size)
 #define xfree(p) xfree_(__FILE__, __LINE__, p)
 #define xcalloc(count, size) xcalloc_(__FILE__, __LINE__, count, size)
+#define xstrdup(s) xstrdup_(__FILE__, __LINE__, s)
 
 /* Use these instead to make it easier to track memory usage. */
 void* xmalloc_(const char* file, int line, size_t);
 void xfree_(const char* file, int line, void*);
 void* xcalloc_(const char* file, int line, size_t, size_t);
+char* xstrdup_(const char* file, int line, const char*);
 
 #else
 
 #define xmalloc malloc
 #define xfree free
 #define xcalloc calloc
+#define xstrdup strdup
 
 #endif