From 7fe48a5a3f65c759adf7ff4b778bcf8a18334c7b Mon Sep 17 00:00:00 2001
From: Nicholas Tay <nick@windblume.net>
Date: Mon, 30 May 2022 21:33:19 +1000
Subject: Add a proper cache for Linux+SDL

---
 platform/linux.c | 64 +++++++++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 50 insertions(+), 14 deletions(-)

(limited to 'platform')

diff --git a/platform/linux.c b/platform/linux.c
index 78e74aa..da8d64c 100644
--- a/platform/linux.c
+++ b/platform/linux.c
@@ -26,6 +26,17 @@ static bool running = true;
 static Display *display;
 static int xi_opcode;
 
+#define AUDIO_CACHE_INITIAL 10
+
+struct mixer_cache {
+	Mix_Chunk *chunk;
+	unsigned char *buffer;
+};
+static struct mixer_cache *cached_chunks = NULL;
+static unsigned int cached_len = 0;
+/* TODO: Add a limit to the capacity? Do we panic if it's hit? */
+static unsigned int cached_capacity = AUDIO_CACHE_INITIAL;
+
 bool sound_init(float volume)
 {
 	if (SDL_Init(SDL_INIT_AUDIO) < 0) {
@@ -33,34 +44,59 @@ bool sound_init(float volume)
 		return false;
 	}
 
-	if (Mix_OpenAudio(MIXER_FREQ, MIXER_FORMAT, MIXER_CHANNELS, MIXER_CHUNKSIZE)) {
+	if (Mix_OpenAudio(MIXER_FREQ, MIXER_FORMAT, MIXER_CHANNELS, MIXER_CHUNKSIZE) < 0) {
 		printf("ERROR: SDL mixer audio device open fail.\n");
 		return false;
 	}
 
+	if ((cached_chunks = malloc(AUDIO_CACHE_INITIAL * sizeof(struct mixer_cache))) == NULL) {
+		printf("ERROR: Could not allocate for audio cache.\n");
+		return false;
+	}
+
 	Mix_Volume(-1, volume * MIX_MAX_VOLUME); // set for all channels
 	return true;
 }
 
-// TODO: get rid of this with proper cache thing - only supports 1 sound for now
-static Mix_Chunk *loaded_chunk = NULL;
+/* Find sample in cache, otherwise load into it */
+static Mix_Chunk *sound_cached(unsigned char *buffer, unsigned int buffer_len) {
+	/* Linear scan for now */
+	for (unsigned int i = 0; i < cached_len; ++i) {
+		struct mixer_cache cached = cached_chunks[i];
+		if (cached.buffer == buffer)
+			return cached.chunk;
+	}
+
+	/* Not in cache; grow if required as well */
+	if (cached_len >= cached_capacity) {
+		cached_capacity += 10;
+		if ((cached_chunks = realloc(cached_chunks, cached_capacity * sizeof(struct mixer_cache))) == NULL) {
+			printf("ERROR: Could not allocate for audio cache!\n");
+			return NULL;
+		}
+	}
+
+	SDL_RWops *sample_rw = SDL_RWFromMem(buffer, buffer_len);
+	Mix_Chunk *chunk = Mix_LoadWAV_RW(sample_rw, 1);
+	if (chunk == NULL) {
+		printf("ERROR: Audio sample could not be loaded - %s\n", Mix_GetError());
+		return NULL;
+	}
+
+	cached_chunks[cached_len++] = (struct mixer_cache){ .chunk = chunk, .buffer = buffer };
+	return chunk;
+}
 
 void sound_play(unsigned char *buffer, unsigned int buffer_len)
 {
-	/* Load sample into SDL memory thing then into the mixer */
-	// TODO: Cache these samples as loaded into SDL
-	if (loaded_chunk == NULL) {
-		SDL_RWops *sample_rw = SDL_RWFromMem(buffer, buffer_len);
-		loaded_chunk = Mix_LoadWAV_RW(sample_rw, 1);
-		if (loaded_chunk == NULL) {
-			printf("ERROR: Sample load fail - %s\n", Mix_GetError());
-			running = false;
-			return;
-		}
+	Mix_Chunk *chunk = sound_cached(buffer, buffer_len);
+	if (chunk == NULL) {
+		running = false;
+		return;
 	}
 
 	/* -1 means not-in-use channel */
-	Mix_PlayChannel(-1, loaded_chunk, 0);
+	Mix_PlayChannel(-1, chunk, 0);
 }
 
 /*
-- 
cgit