sound: sandbox: Use the correct frequency

At present we request a particular frequency but we may not get the exact
same frequency in response. So use the actual frequency for generation of
the square wave. This ensures that the pitch remains accurate on all host
machines.

Signed-off-by: Simon Glass <sjg@chromium.org>

1 files changed, 9 insertions, 2 deletions

diff --git a/arch/sandbox/cpu/sdl.c b/arch/sandbox/cpu/sdl.c
index 36f1bf0..c940a47 100644
--- a/arch/sandbox/cpu/sdl.c
+++ b/arch/sandbox/cpu/sdl.c
@@ -9,6 +9,10 @@
 #include <sound.h>
 #include <asm/state.h>
 
+enum {
+	SAMPLE_RATE	= 22050,
+};
+
 static struct sdl_info {
 	SDL_Surface *screen;
 	int width;
@@ -18,6 +22,7 @@ static struct sdl_info {
 	uint frequency;
 	uint audio_pos;
 	uint audio_size;
+	uint sample_rate;
 	uint8_t *audio_data;
 	bool audio_active;
 	bool inited;
@@ -283,7 +288,7 @@ int sandbox_sdl_sound_init(void)
 	return 0;
 
 	/* Set the audio format */
-	wanted.freq = 22050;
+	wanted.freq = SAMPLE_RATE;
 	wanted.format = AUDIO_S16;
 	wanted.channels = 1;    /* 1 = mono, 2 = stereo */
 	wanted.samples = 1024;  /* Good low-latency value for callback */
@@ -309,6 +314,7 @@ int sandbox_sdl_sound_init(void)
 		goto err;
 	}
 	sdl.audio_active = true;
+	sdl.sample_rate = wanted.freq;
 
 	return 0;
 
@@ -322,7 +328,8 @@ int sandbox_sdl_sound_start(uint frequency)
 	if (!sdl.audio_active)
 		return -1;
 	sdl.frequency = frequency;
-	sound_create_square_wave(22050, (unsigned short *)sdl.audio_data,
+	sound_create_square_wave(sdl.sample_rate,
+				 (unsigned short *)sdl.audio_data,
 				 sdl.audio_size, frequency);
 	sdl.audio_pos = 0;
 	SDL_PauseAudio(0);