medfall

commit 8724d6d2f2b8e32fc9b9baf767c1e231cda91994
parent 771d40488392a6cb1b755a45fe664bd992bb7ad0
Author: Michael Savage <mikejsavage@gmail.com>
Date:   Sat Oct 31 23:24:41 +0000

Add WAV decoder

Diffstat:
intrinsics.h
 | 
11
++++++++---
wave.cc
 | 
103
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
wave.h
 | 
16
++++++++++++++++
3 files changed, 127 insertions(+), 3 deletions(-)
diff --git a/intrinsics.h b/intrinsics.h
@@ -23,6 +23,7 @@ typedef double f64;
 #define is_power_of_2( n ) ( ( ( n ) & ( ( n ) - 1 ) ) == 0 )
 
 #define align_power_of_2( n, alignment ) ( ( ( n ) + ( alignment ) - 1 ) & ~( ( alignment ) - 1 ) )
+#define align2( n ) align_power_of_2( n, 4 )
 #define align4( n ) align_power_of_2( n, 4 )
 #define align8( n ) align_power_of_2( n, 8 )
 #define align16( n ) align_power_of_2( n, 16 )
@@ -30,18 +31,22 @@ typedef double f64;
 // TODO: clashes with some crap in std::string
 #define align_TODO( n, alignment ) ( ( ( n ) + ( alignment ) - 1 ) / ( alignment ) * ( alignment ) )
 
-inline size_t kilobytes( const size_t kb ) {
+inline constexpr size_t kilobytes( const size_t kb ) {
 	return kb * 1024;
 }
 
-inline size_t megabytes( const size_t mb ) {
+inline constexpr size_t megabytes( const size_t mb ) {
 	return kilobytes( mb ) * 1024;
 }
 
-inline size_t gigabytes( const size_t gb ) {
+inline constexpr size_t gigabytes( const size_t gb ) {
 	return megabytes( gb ) * 1024;
 }
 
+inline u32 min_u32( u32 a, u32 b ) {
+	return a < b ? a : b;
+}
+
 inline u32 max_u32( u32 a, u32 b ) {
 	return a > b ? a : b;
 }
diff --git a/wave.cc b/wave.cc
@@ -0,0 +1,103 @@
+#include "intrinsics.h"
+#include "memory_arena.h"
+#include "wave.h"
+
+// TODO: this only works on a little endian machine
+
+#define WAVEID( a, b, c, d ) ( d << 24 ) | ( c << 16 ) | ( b << 8 ) | a
+
+enum WaveID {
+	WAVEID_RIFF = WAVEID( 'R', 'I', 'F', 'F' ),
+	WAVEID_WAVE = WAVEID( 'W', 'A', 'V', 'E' ),
+	WAVEID_fmt = WAVEID( 'f', 'm', 't', ' ' ),
+	WAVEID_data = WAVEID( 'd', 'a', 't', 'a' ),
+};
+
+struct WaveHeader {
+	u32 id_riff;
+	u32 length;
+	u32 id_wave;
+};
+
+struct WaveChunk {
+	u32 id;
+	u32 length;
+};
+
+struct WaveFMT {
+	u32 id;
+	u32 length;
+
+	u16 format;
+	u16 num_channels;
+	u32 sample_rate;
+	u32 data_rate;
+	u16 block_align;
+	u16 bits_per_sample;
+};
+
+bool wave_decode( MemoryArena * arena, u8 * data, Sound * sound ) {
+	WaveHeader * header = ( WaveHeader * ) data;
+
+	if( header->id_riff != WAVEID_RIFF || header->id_wave != WAVEID_WAVE ) {
+		printf( "bad header\n" );
+		return false;
+	}
+
+	u32 pos = sizeof( WaveHeader );
+	u32 data_length;
+
+	while( pos < header->length ) {
+		WaveChunk * chunk = ( WaveChunk * ) ( data + pos );
+
+		switch( chunk->id ) {
+			case WAVEID_fmt: {
+				if( chunk->length != 16 ) return false;
+
+				WaveFMT * fmt = ( WaveFMT * ) chunk;
+
+				if( ( fmt->num_channels != 1 && fmt->num_channels != 2 ) || fmt->bits_per_sample != 16 ) {
+					return false;
+				}
+
+				sound->num_channels = fmt->num_channels;
+				sound->sample_rate = fmt->sample_rate;
+
+				break;
+			}
+
+			case WAVEID_data: {
+				sound->samples = ( s16 * ) ( chunk + 1 );
+				data_length = chunk->length;
+				break;
+			};
+
+			default: {
+				printf( "wtf is this\n" );
+				return false;
+			}
+		}
+
+		pos += sizeof( WaveChunk ) + align2( chunk->length );
+	}
+
+	sound->num_samples = data_length / ( sound->num_channels * sizeof( s16 ) );
+
+	// uninterleave the samples
+	if( sound->num_channels == 2 ) {
+		MEMARENA_SCOPED_CHECKPOINT( arena );
+		printf( "%u\n", sound->num_samples * 2 );
+		s16 * scratch = memarena_push_many( arena, s16, sound->num_samples * 2 );
+
+		for( u32 i = 0; i < sound->num_samples; i++ ) {
+			scratch[ i ] = sound->samples[ i * 2 ];
+			scratch[ i + sound->num_samples ] = sound->samples[ i * 2 + 1 ];
+		}
+
+		for( u32 i = 0; i < sound->num_samples * 2; i++ ) {
+			sound->samples[ i ] = scratch[ i ];
+		}
+	}
+
+	return true;
+}
diff --git a/wave.h b/wave.h
@@ -0,0 +1,16 @@
+#ifndef _WAVE_H_
+#define _WAVE_H_
+
+#include "memory_arena.h"
+
+struct Sound {
+	u32 num_samples;
+	u32 sample_rate;
+	u32 num_channels;
+
+	s16 * samples;
+};
+
+bool wave_decode( MemoryArena * arena, u8 * data, Sound * sound );
+
+#endif // _WAVE_H_