webp: Make it a module and unbundle libwebp thirdparty files

Note that there are two Godot-specific changes made to libwebp
for the javascript/HTML5 platform. They are documented in the
README.md.

(cherry picked from commit ee3cf211c6)

thirdparty/libwebp/utils/utils.h

@@ -0,0 +1,182 @@
+// 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.
+// -----------------------------------------------------------------------------
+//
+// Misc. common utility functions
+//
+// Authors: Skal (pascal.massimino@gmail.com)
+//          Urvang (urvang@google.com)
+
+#ifndef WEBP_UTILS_UTILS_H_
+#define WEBP_UTILS_UTILS_H_
+
+#ifdef HAVE_CONFIG_H
+#include "../webp/config.h"
+#endif
+
+#include <assert.h>
+
+#include "../dsp/dsp.h"
+#include "../webp/types.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+//------------------------------------------------------------------------------
+// Memory allocation
+
+// This is the maximum memory amount that libwebp will ever try to allocate.
+#define WEBP_MAX_ALLOCABLE_MEMORY (1ULL << 40)
+
+// size-checking safe malloc/calloc: verify that the requested size is not too
+// large, or return NULL. You don't need to call these for constructs like
+// malloc(sizeof(foo)), but only if there's picture-dependent size involved
+// somewhere (like: malloc(num_pixels * sizeof(*something))). That's why this
+// safe malloc() borrows the signature from calloc(), pointing at the dangerous
+// underlying multiply involved.
+WEBP_EXTERN(void*) WebPSafeMalloc(uint64_t nmemb, size_t size);
+// Note that WebPSafeCalloc() expects the second argument type to be 'size_t'
+// in order to favor the "calloc(num_foo, sizeof(foo))" pattern.
+WEBP_EXTERN(void*) WebPSafeCalloc(uint64_t nmemb, size_t size);
+
+// Companion deallocation function to the above allocations.
+WEBP_EXTERN(void) WebPSafeFree(void* const ptr);
+
+//------------------------------------------------------------------------------
+// Alignment
+
+#define WEBP_ALIGN_CST 31
+#define WEBP_ALIGN(PTR) (((uintptr_t)(PTR) + WEBP_ALIGN_CST) & ~WEBP_ALIGN_CST)
+
+#if defined(WEBP_FORCE_ALIGNED)
+#include <string.h>
+// memcpy() is the safe way of moving potentially unaligned 32b memory.
+static WEBP_INLINE uint32_t WebPMemToUint32(const uint8_t* const ptr) {
+  uint32_t A;
+  memcpy(&A, (const int*)ptr, sizeof(A));
+  return A;
+}
+static WEBP_INLINE void WebPUint32ToMem(uint8_t* const ptr, uint32_t val) {
+  memcpy(ptr, &val, sizeof(val));
+}
+#else
+static WEBP_UBSAN_IGNORE_UNDEF WEBP_INLINE
+uint32_t WebPMemToUint32(const uint8_t* const ptr) {
+  return *(const uint32_t*)ptr;
+}
+static WEBP_UBSAN_IGNORE_UNDEF WEBP_INLINE
+void WebPUint32ToMem(uint8_t* const ptr, uint32_t val) {
+  *(uint32_t*)ptr = val;
+}
+#endif
+
+//------------------------------------------------------------------------------
+// Reading/writing data.
+
+// Read 16, 24 or 32 bits stored in little-endian order.
+static WEBP_INLINE int GetLE16(const uint8_t* const data) {
+  return (int)(data[0] << 0) | (data[1] << 8);
+}
+
+static WEBP_INLINE int GetLE24(const uint8_t* const data) {
+  return GetLE16(data) | (data[2] << 16);
+}
+
+static WEBP_INLINE uint32_t GetLE32(const uint8_t* const data) {
+  return GetLE16(data) | ((uint32_t)GetLE16(data + 2) << 16);
+}
+
+// Store 16, 24 or 32 bits in little-endian order.
+static WEBP_INLINE void PutLE16(uint8_t* const data, int val) {
+  assert(val < (1 << 16));
+  data[0] = (val >> 0);
+  data[1] = (val >> 8);
+}
+
+static WEBP_INLINE void PutLE24(uint8_t* const data, int val) {
+  assert(val < (1 << 24));
+  PutLE16(data, val & 0xffff);
+  data[2] = (val >> 16);
+}
+
+static WEBP_INLINE void PutLE32(uint8_t* const data, uint32_t val) {
+  PutLE16(data, (int)(val & 0xffff));
+  PutLE16(data + 2, (int)(val >> 16));
+}
+
+// Returns (int)floor(log2(n)). n must be > 0.
+// use GNU builtins where available.
+#if defined(__GNUC__) && \
+    ((__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || __GNUC__ >= 4)
+static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
+  return 31 ^ __builtin_clz(n);
+}
+#elif defined(_MSC_VER) && _MSC_VER > 1310 && \
+      (defined(_M_X64) || defined(_M_IX86))
+#include <intrin.h>
+#pragma intrinsic(_BitScanReverse)
+
+static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
+  unsigned long first_set_bit;
+  _BitScanReverse(&first_set_bit, n);
+  return first_set_bit;
+}
+#else
+static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
+  int log = 0;
+  uint32_t value = n;
+  int i;
+
+  for (i = 4; i >= 0; --i) {
+    const int shift = (1 << i);
+    const uint32_t x = value >> shift;
+    if (x != 0) {
+      value = x;
+      log += shift;
+    }
+  }
+  return log;
+}
+#endif
+
+//------------------------------------------------------------------------------
+// Pixel copying.
+
+struct WebPPicture;
+
+// Copy width x height pixels from 'src' to 'dst' honoring the strides.
+WEBP_EXTERN(void) WebPCopyPlane(const uint8_t* src, int src_stride,
+                                uint8_t* dst, int dst_stride,
+                                int width, int height);
+
+// Copy ARGB pixels from 'src' to 'dst' honoring strides. 'src' and 'dst' are
+// assumed to be already allocated and using ARGB data.
+WEBP_EXTERN(void) WebPCopyPixels(const struct WebPPicture* const src,
+                                 struct WebPPicture* const dst);
+
+//------------------------------------------------------------------------------
+// Unique colors.
+
+// Returns count of unique colors in 'pic', assuming pic->use_argb is true.
+// If the unique color count is more than MAX_COLOR_COUNT, returns
+// MAX_COLOR_COUNT+1.
+// If 'palette' is not NULL and number of unique colors is less than or equal to
+// MAX_COLOR_COUNT, also outputs the actual unique colors into 'palette'.
+// Note: 'palette' is assumed to be an array already allocated with at least
+// MAX_COLOR_COUNT elements.
+WEBP_EXTERN(int) WebPGetColorPalette(const struct WebPPicture* const pic,
+                                     uint32_t* const palette);
+
+//------------------------------------------------------------------------------
+
+#ifdef __cplusplus
+}    // extern "C"
+#endif
+
+#endif  /* WEBP_UTILS_UTILS_H_ */