src/{dec,enc,utils}: give filenames a unique suffix

this avoids duplicates between these trees and dsp/, e.g., enc/tree.c,
dec/tree.c, making pulling the whole library source tree into one target
possible

BUG=webp:279

Change-Id: I060a614833c7c24ddd37bf641702ae6a5eef1775

src/utils/rescaler_utils.h

@@ -0,0 +1,101 @@
+// Copyright 2012 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+// Rescaling functions
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#ifndef WEBP_UTILS_RESCALER_H_
+#define WEBP_UTILS_RESCALER_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "../webp/types.h"
+
+#define WEBP_RESCALER_RFIX 32   // fixed-point precision for multiplies
+#define WEBP_RESCALER_ONE (1ull << WEBP_RESCALER_RFIX)
+#define WEBP_RESCALER_FRAC(x, y) \
+    ((uint32_t)(((uint64_t)(x) << WEBP_RESCALER_RFIX) / (y)))
+
+// Structure used for on-the-fly rescaling
+typedef uint32_t rescaler_t;   // type for side-buffer
+typedef struct WebPRescaler WebPRescaler;
+struct WebPRescaler {
+  int x_expand;               // true if we're expanding in the x direction
+  int y_expand;               // true if we're expanding in the y direction
+  int num_channels;           // bytes to jump between pixels
+  uint32_t fx_scale;          // fixed-point scaling factors
+  uint32_t fy_scale;          // ''
+  uint32_t fxy_scale;         // ''
+  int y_accum;                // vertical accumulator
+  int y_add, y_sub;           // vertical increments
+  int x_add, x_sub;           // horizontal increments
+  int src_width, src_height;  // source dimensions
+  int dst_width, dst_height;  // destination dimensions
+  int src_y, dst_y;           // row counters for input and output
+  uint8_t* dst;
+  int dst_stride;
+  rescaler_t* irow, *frow;    // work buffer
+};
+
+// Initialize a rescaler given scratch area 'work' and dimensions of src & dst.
+void WebPRescalerInit(WebPRescaler* const rescaler,
+                      int src_width, int src_height,
+                      uint8_t* const dst,
+                      int dst_width, int dst_height, int dst_stride,
+                      int num_channels,
+                      rescaler_t* const work);
+
+// If either 'scaled_width' or 'scaled_height' (but not both) is 0 the value
+// will be calculated preserving the aspect ratio, otherwise the values are
+// left unmodified. Returns true on success, false if either value is 0 after
+// performing the scaling calculation.
+int WebPRescalerGetScaledDimensions(int src_width, int src_height,
+                                    int* const scaled_width,
+                                    int* const scaled_height);
+
+// Returns the number of input lines needed next to produce one output line,
+// considering that the maximum available input lines are 'max_num_lines'.
+int WebPRescaleNeededLines(const WebPRescaler* const rescaler,
+                           int max_num_lines);
+
+// Import multiple rows over all channels, until at least one row is ready to
+// be exported. Returns the actual number of lines that were imported.
+int WebPRescalerImport(WebPRescaler* const rescaler, int num_rows,
+                       const uint8_t* src, int src_stride);
+
+// Export as many rows as possible. Return the numbers of rows written.
+int WebPRescalerExport(WebPRescaler* const rescaler);
+
+// Return true if input is finished
+static WEBP_INLINE
+int WebPRescalerInputDone(const WebPRescaler* const rescaler) {
+  return (rescaler->src_y >= rescaler->src_height);
+}
+// Return true if output is finished
+static WEBP_INLINE
+int WebPRescalerOutputDone(const WebPRescaler* const rescaler) {
+  return (rescaler->dst_y >= rescaler->dst_height);
+}
+
+// Return true if there are pending output rows ready.
+static WEBP_INLINE
+int WebPRescalerHasPendingOutput(const WebPRescaler* const rescaler) {
+  return !WebPRescalerOutputDone(rescaler) && (rescaler->y_accum <= 0);
+}
+
+//------------------------------------------------------------------------------
+
+#ifdef __cplusplus
+}    // extern "C"
+#endif
+
+#endif  /* WEBP_UTILS_RESCALER_H_ */