Reworked audio converter code.

This no longer uses a script to generate code for every possible type
conversion or resampler. This caused a bloat in binary size and and compile
times. Now we use a handful of more generic functions and assume staying in
the CPU cache is the most important thing anyhow.

This shrinks the size of the final build (in this case: macOS X amd64, -Os to
optimize for size) by 15%. When compiling on a single core, build times drop
by about 15% too (although the previous cost was largely hidden by multicore
builds).

src/audio/SDL_audio_c.h

@@ -20,6 +20,16 @@
 */
 #include "../SDL_internal.h"
 
+#ifndef DEBUG_CONVERT
+#define DEBUG_CONVERT 0
+#endif
+
+#if DEBUG_CONVERT
+#define LOG_DEBUG_CONVERT(from, to) fprintf(stderr, "Converting %s to %s.\n", from, to);
+#else
+#define LOG_DEBUG_CONVERT(from, to)
+#endif
+
 /* Functions and variables exported from SDL_audio.c for SDL_sysaudio.c */
 
 /* Functions to get a list of "close" audio formats */
@@ -29,24 +39,20 @@ extern SDL_AudioFormat SDL_NextAudioFormat(void);
 /* Function to calculate the size and silence for a SDL_AudioSpec */
 extern void SDL_CalculateAudioSpec(SDL_AudioSpec * spec);
 
-/* this is used internally to access some autogenerated code. */
-typedef struct
-{
-    SDL_AudioFormat src_fmt;
-    SDL_AudioFormat dst_fmt;
-    SDL_AudioFilter filter;
-} SDL_AudioTypeFilters;
-extern const SDL_AudioTypeFilters sdl_audio_type_filters[];
-
-/* this is used internally to access some autogenerated code. */
-typedef struct
-{
-    SDL_AudioFormat fmt;
-    int channels;
-    int upsample;
-    int multiple;
-    SDL_AudioFilter filter;
-} SDL_AudioRateFilters;
-extern const SDL_AudioRateFilters sdl_audio_rate_filters[];
+void SDLCALL SDL_Convert_S8_to_F32(SDL_AudioCVT *cvt, SDL_AudioFormat format);
+void SDLCALL SDL_Convert_U8_to_F32(SDL_AudioCVT *cvt, SDL_AudioFormat format);
+void SDLCALL SDL_Convert_S16_to_F32(SDL_AudioCVT *cvt, SDL_AudioFormat format);
+void SDLCALL SDL_Convert_U16_to_F32(SDL_AudioCVT *cvt, SDL_AudioFormat format);
+void SDLCALL SDL_Convert_S32_to_F32(SDL_AudioCVT *cvt, SDL_AudioFormat format);
+void SDLCALL SDL_Convert_F32_to_S8(SDL_AudioCVT *cvt, SDL_AudioFormat format);
+void SDLCALL SDL_Convert_F32_to_U8(SDL_AudioCVT *cvt, SDL_AudioFormat format);
+void SDLCALL SDL_Convert_F32_to_S16(SDL_AudioCVT *cvt, SDL_AudioFormat format);
+void SDLCALL SDL_Convert_F32_to_U16(SDL_AudioCVT *cvt, SDL_AudioFormat format);
+void SDLCALL SDL_Convert_F32_to_S32(SDL_AudioCVT *cvt, SDL_AudioFormat format);
+void SDL_Upsample_Arbitrary(SDL_AudioCVT *cvt, const int channels);
+void SDL_Downsample_Arbitrary(SDL_AudioCVT *cvt, const int channels);
+void SDL_Upsample_x2(SDL_AudioCVT *cvt, const int channels);
+void SDL_Upsample_x4(SDL_AudioCVT *cvt, const int channels);
+void SDL_Downsample_Multiple(SDL_AudioCVT *cvt, const int multiple, const int channels);
 
 /* vi: set ts=4 sw=4 expandtab: */