move dithering into plugin_common library

src/plugin_winamp2/in_flac.c

@@ -28,6 +28,7 @@
 
 #include "in2.h"
 #include "FLAC/all.h"
+#include "plugin_common/all.h"
 
 #ifdef max
 #undef max
@@ -93,134 +94,6 @@ HANDLE thread_handle = INVALID_HANDLE_VALUE;	/* the handle to the decode thread
 DWORD WINAPI __stdcall DecodeThread(void *b); /* the decode thread procedure */
 
 
-/* 32-bit pseudo-random number generator */
-static __inline FLAC__uint32 prng(FLAC__uint32 state)
-{
-	return (state * 0x0019660dL + 0x3c6ef35fL) & 0xffffffffL;
-}
-
-/* dither routine derived from MAD winamp plugin */
-
-typedef struct {
-	FLAC__int32 error[3];
-	FLAC__int32 random;
-} dither_state;
-
-static __inline FLAC__int32 linear_dither(unsigned source_bps, unsigned target_bps, FLAC__int32 sample, dither_state *dither, const FLAC__int32 MIN, const FLAC__int32 MAX)
-{
-	unsigned scalebits;
-	FLAC__int32 output, mask, random;
-
-	FLAC__ASSERT(source_bps < 32);
-	FLAC__ASSERT(target_bps <= 24);
-	FLAC__ASSERT(target_bps <= source_bps);
-
-	/* noise shape */
-	sample += dither->error[0] - dither->error[1] + dither->error[2];
-
-	dither->error[2] = dither->error[1];
-	dither->error[1] = dither->error[0] / 2;
-
-	/* bias */
-	output = sample + (1L << (source_bps - target_bps - 1));
-
-	scalebits = source_bps - target_bps;
-	mask = (1L << scalebits) - 1;
-
-	/* dither */
-	random = (FLAC__int32)prng(dither->random);
-	output += (random & mask) - (dither->random & mask);
-
-	dither->random = random;
-
-	/* clip */
-	if(output > MAX) {
-		output = MAX;
-
-		if(sample > MAX)
-			sample = MAX;
-	}
-	else if(output < MIN) {
-		output = MIN;
-
-		if(sample < MIN)
-			sample = MIN;
-	}
-
-	/* quantize */
-	output &= ~mask;
-
-	/* error feedback */
-	dither->error[0] = sample - output;
-
-	/* scale */
-	return output >> scalebits;
-}
-
-static unsigned pack_pcm(FLAC__byte *data, FLAC__int32 *input, unsigned wide_samples, unsigned channels, unsigned source_bps, unsigned target_bps)
-{
-	static dither_state dither[MAX_SUPPORTED_CHANNELS];
-	FLAC__byte * const start = data;
-	FLAC__int32 sample;
-	unsigned samples = wide_samples * channels;
-	const unsigned bytes_per_sample = target_bps / 8;
-
-	FLAC__ASSERT(MAX_SUPPORTED_CHANNELS == 2);
-	FLAC__ASSERT(channels > 0 && channels <= MAX_SUPPORTED_CHANNELS);
-	FLAC__ASSERT(source_bps < 32);
-	FLAC__ASSERT(target_bps <= 24);
-	FLAC__ASSERT(target_bps <= source_bps);
-	FLAC__ASSERT(source_bps & 7 == 0);
-	FLAC__ASSERT(target_bps & 7 == 0);
-
-	if(source_bps != target_bps) {
-		const FLAC__int32 MIN = -(1L << source_bps);
-		const FLAC__int32 MAX = ~MIN; /*(1L << (source_bps-1)) - 1 */
-		const unsigned dither_twiggle = channels - 1;
-		unsigned dither_source = 0;
-
-		while(samples--) {
-			sample = linear_dither(source_bps, target_bps, *input++, &dither[dither_source], MIN, MAX);
-			dither_source ^= dither_twiggle;
-
-			switch(target_bps) {
-				case 8:
-					data[0] = sample ^ 0x80;
-					break;
-				case 24:
-					data[2] = (FLAC__byte)(sample >> 16);
-					/* fall through */
-				case 16:
-					data[1] = (FLAC__byte)(sample >> 8);
-					data[0] = (FLAC__byte)sample;
-			}
-
-			data += bytes_per_sample;
-		}
-	}
-	else {
-		while(samples--) {
-			sample = *input++;
-
-			switch(target_bps) {
-				case 8:
-					data[0] = sample ^ 0x80;
-					break;
-				case 24:
-					data[2] = (FLAC__byte)(sample >> 16);
-					/* fall through */
-				case 16:
-					data[1] = (FLAC__byte)(sample >> 8);
-					data[0] = (FLAC__byte)sample;
-			}
-
-			data += bytes_per_sample;
-		}
-	}
-
-	return data - start;
-}
-
 #if 0
 @@@@ incorporate this
 static void do_vis(char *data, int nch, int resolution, int position)
@@ -480,7 +353,7 @@ DWORD WINAPI __stdcall DecodeThread(void *b)
 #endif
 				const unsigned n = min(wide_samples_in_reservoir_, 576);
 				const unsigned delta = n * channels;
-				int bytes = (int)pack_pcm(sample_buffer_, reservoir_, n, channels, bits_per_sample, target_bps);
+				int bytes = (int)FLAC__plugin_common__pack_pcm(sample_buffer_, reservoir_, n, channels, bits_per_sample, target_bps);
 				unsigned i;
 
 				for(i = delta; i < wide_samples_in_reservoir_ * channels; i++)