create a separate libwebpdsp under src/dsp

Gathers all DSP-related function (and SSE2 implementations).
Clean-up some unwanted symbolic dependencies so that webp_encode,
webp_decode and webp_dsp are truly independent libraries.

+ opportunistic clean-up:
  * remove unneeded VP8DspInitTables(), now integrated in VP8DspInit()
  * make consistent use of VP8GetCPUInfo() in the various DspInit() funcs
  * change OUT macro to DST

src/enc/Makefile.am

@@ -1,9 +1,10 @@
 AM_CPPFLAGS = -I$(top_srcdir)/src
 
 libwebpencode_la_SOURCES = analysis.c bit_writer.c bit_writer.h \
-                          config.c cost.c cost.h dsp.c dsp_sse2.c filter.c \
-                          frame.c iterator.c picture.c quant.c  \
-                          syntax.c tree.c vp8enci.h webpenc.c alpha.c layer.c
+                           config.c cost.c cost.h filter.c \
+                           frame.c iterator.c picture.c quant.c  \
+                           syntax.c tree.c vp8enci.h webpenc.c alpha.c \
+                           layer.c
 libwebpencode_la_LDFLAGS = -version-info 0:0:0 -lm
 libwebpencode_la_CPPFLAGS = $(USE_EXPERIMENTAL_CODE)
 libwebpencodeinclude_HEADERS = ../webp/encode.h ../webp/types.h
@@ -11,6 +12,3 @@ libwebpencodeincludedir = $(includedir)/webp
 
 noinst_HEADERS = cost.h bit_writer.h vp8enci.h
 noinst_LTLIBRARIES = libwebpencode.la
-# uncomment the following line (and comment the above) if you want
-# to install libwebpencode library.
-#lib_LTLIBRARIES = libwebpencode.la

src/enc/quant.c

@@ -39,7 +39,7 @@ static inline int clip(int v, int m, int M) {
   return v < m ? m : v > M ? M : v;
 }
 
-const uint8_t VP8Zigzag[16] = {
+static const uint8_t kZigzag[16] = {
   0, 1, 4, 8, 5, 2, 3, 6, 9, 12, 13, 10, 7, 11, 14, 15
 };
 
@@ -143,7 +143,7 @@ static int ExpandMatrix(VP8Matrix* const m, int type) {
     m->q_[i] = m->q_[1];
   }
   for (i = 0; i < 16; ++i) {
-    const int j = VP8Zigzag[i];
+    const int j = kZigzag[i];
     const int bias = kBiasMatrices[type][j];
     m->iq_[j] = (1 << QFIX) / m->q_[j];
     m->bias_[j] = BIAS(bias);
@@ -440,7 +440,7 @@ static int TrellisQuantizeBlock(const VP8EncIterator* const it,
     // compute maximal distortion.
     max_error = 0;
     for (n = first; n < 16; ++n) {
-      const int j  = VP8Zigzag[n];
+      const int j  = kZigzag[n];
       const int err = in[j] * in[j];
       max_error += kWeightTrellis[j] * err;
       if (err > thresh) last = n;
@@ -464,7 +464,7 @@ static int TrellisQuantizeBlock(const VP8EncIterator* const it,
 
   // traverse trellis.
   for (n = first; n <= last; ++n) {
-    const int j  = VP8Zigzag[n];
+    const int j  = kZigzag[n];
     const int Q  = mtx->q_[j];
     const int iQ = mtx->iq_[j];
     const int B = BIAS(0x00);     // neutral bias
@@ -560,7 +560,7 @@ static int TrellisQuantizeBlock(const VP8EncIterator* const it,
 
   for (; n >= first; --n) {
     const Node* const node = &NODE(n, best_node);
-    const int j = VP8Zigzag[n];
+    const int j = kZigzag[n];
     out[n] = node->sign ? -node->level : node->level;
     nz |= (node->level != 0);
     in[j] = out[n] * mtx->q_[j];

src/enc/vp8enci.h

@@ -14,6 +14,7 @@
 
 #include "string.h"     // for memcpy()
 #include "../webp/encode.h"
+#include "../dsp/dsp.h"
 #include "bit_writer.h"
 
 #if defined(__cplusplus) || defined(c_plusplus)
@@ -211,7 +212,7 @@ typedef struct {
   uint8_t alpha_;      // quantization-susceptibility
 } VP8MBInfo;
 
-typedef struct {
+typedef struct VP8Matrix {
   uint16_t q_[16];        // quantizer steps
   uint16_t iq_[16];       // reciprocals, fixed point.
   uint16_t bias_[16];     // rounding bias
@@ -421,12 +422,8 @@ int VP8StatLoop(VP8Encoder* const enc);
   // in webpenc.c
 // Assign an error code to a picture. Return false for convenience.
 int WebPEncodingSetError(WebPPicture* const pic, WebPEncodingError error);
+
   // in analysis.c
-// Compute susceptibility based on DCT-coeff histograms:
-// the higher, the "easier" the macroblock is to compress.
-typedef int (*VP8CHisto)(const uint8_t* ref, const uint8_t* pred,
-                         int start_block, int end_block);
-extern VP8CHisto VP8CollectHistogram;
 // Main analysis loop. Decides the segmentations and complexity.
 // Assigns a first guess for Intra16 and uvmode_ prediction modes.
 int VP8EncAnalyze(VP8Encoder* const enc);
@@ -449,54 +446,6 @@ void VP8EncCodeLayerBlock(VP8EncIterator* it);   // code one more macroblock
 int VP8EncFinishLayer(VP8Encoder* const enc);    // finalize coding
 void VP8EncDeleteLayer(VP8Encoder* enc);         // reclaim memory
 
-  // in dsp.c
-int VP8GetAlpha(const int histo[MAX_COEFF_THRESH + 1]);
-
-// Transforms
-// VP8Idct: Does one of two inverse transforms. If do_two is set, the transforms
-//          will be done for (ref, in, dst) and (ref + 4, in + 16, dst + 4).
-typedef void (*VP8Idct)(const uint8_t* ref, const int16_t* in, uint8_t* dst,
-                        int do_two);
-typedef void (*VP8Fdct)(const uint8_t* src, const uint8_t* ref, int16_t* out);
-typedef void (*VP8WHT)(const int16_t* in, int16_t* out);
-extern VP8Idct VP8ITransform;
-extern VP8Fdct VP8FTransform;
-extern VP8WHT VP8ITransformWHT;
-extern VP8WHT VP8FTransformWHT;
-// Predictions
-// *dst is the destination block. *top, *top_right and *left can be NULL.
-typedef void (*VP8IntraPreds)(uint8_t *dst, const uint8_t* left,
-                              const uint8_t* top);
-typedef void (*VP8Intra4Preds)(uint8_t *dst, const uint8_t* top);
-extern VP8Intra4Preds VP8EncPredLuma4;
-extern VP8IntraPreds VP8EncPredLuma16;
-extern VP8IntraPreds VP8EncPredChroma8;
-
-typedef int (*VP8Metric)(const uint8_t* pix, const uint8_t* ref);
-extern VP8Metric VP8SSE16x16, VP8SSE16x8, VP8SSE8x8, VP8SSE4x4;
-typedef int (*VP8WMetric)(const uint8_t* pix, const uint8_t* ref,
-                          const uint16_t* const weights);
-extern VP8WMetric VP8TDisto4x4, VP8TDisto16x16;
-
-typedef void (*VP8BlockCopy)(const uint8_t* src, uint8_t* dst);
-extern VP8BlockCopy VP8Copy4x4;
-extern VP8BlockCopy VP8Copy8x8;
-extern VP8BlockCopy VP8Copy16x16;
-// Quantization
-typedef int (*VP8QuantizeBlock)(int16_t in[16], int16_t out[16],
-                                int n, const VP8Matrix* const mtx);
-extern VP8QuantizeBlock VP8EncQuantizeBlock;
-
-typedef enum {
-  kSSE2,
-  kSSE3
-} CPUFeature;
-// returns true if the CPU supports the feature.
-typedef int (*VP8CPUInfo)(CPUFeature feature);
-extern VP8CPUInfo VP8EncGetCPUInfo;
-
-void VP8EncDspInit(void);   // must be called before using any of the above
-
   // in filter.c
 extern void VP8InitFilter(VP8EncIterator* const it);
 extern void VP8StoreFilterStats(VP8EncIterator* const it);