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/*
* Copyright 2014 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef GrProgramDesc_DEFINED
#define GrProgramDesc_DEFINED
#include "GrColor.h"
#include "GrTypesPriv.h"
#include "SkChecksum.h"
class GrGLGpu;
/** This class describes a program to generate. It also serves as a program cache key. Very little
of this is GL-specific. The GL-specific parts could be factored out into a subclass. */
class GrProgramDesc {
public:
// Creates an uninitialized key that must be populated by GrGpu::buildProgramDesc()
GrProgramDesc() {}
// Returns this as a uint32_t array to be used as a key in the program cache.
const uint32_t* asKey() const {
return reinterpret_cast<const uint32_t*>(fKey.begin());
}
// Gets the number of bytes in asKey(). It will be a 4-byte aligned value. When comparing two
// keys the size of either key can be used with memcmp() since the lengths themselves begin the
// keys and thus the memcmp will exit early if the keys are of different lengths.
uint32_t keyLength() const { return *this->atOffset<uint32_t, kLengthOffset>(); }
// Gets the a checksum of the key. Can be used as a hash value for a fast lookup in a cache.
uint32_t getChecksum() const { return *this->atOffset<uint32_t, kChecksumOffset>(); }
GrProgramDesc& operator= (const GrProgramDesc& other) {
uint32_t keyLength = other.keyLength();
fKey.reset(SkToInt(keyLength));
memcpy(fKey.begin(), other.fKey.begin(), keyLength);
return *this;
}
bool operator== (const GrProgramDesc& other) const {
// The length is masked as a hint to the compiler that the address will be 4 byte aligned.
return 0 == memcmp(this->asKey(), other.asKey(), this->keyLength() & ~0x3);
}
bool operator!= (const GrProgramDesc& other) const {
return !(*this == other);
}
static bool Less(const GrProgramDesc& a, const GrProgramDesc& b) {
return memcmp(a.asKey(), b.asKey(), a.keyLength() & ~0x3) < 0;
}
struct KeyHeader {
uint8_t fFragPosKey; // set by GrGLShaderBuilder if there are
// effects that read the fragment position.
// Otherwise, 0.
int8_t fColorEffectCnt;
int8_t fCoverageEffectCnt;
};
int numColorEffects() const {
return this->header().fColorEffectCnt;
}
int numCoverageEffects() const {
return this->header().fCoverageEffectCnt;
}
int numTotalEffects() const { return this->numColorEffects() + this->numCoverageEffects(); }
// This should really only be used internally, base classes should return their own headers
const KeyHeader& header() const { return *this->atOffset<KeyHeader, kHeaderOffset>(); }
private:
template<typename T, size_t OFFSET> T* atOffset() {
return reinterpret_cast<T*>(reinterpret_cast<intptr_t>(fKey.begin()) + OFFSET);
}
template<typename T, size_t OFFSET> const T* atOffset() const {
return reinterpret_cast<const T*>(reinterpret_cast<intptr_t>(fKey.begin()) + OFFSET);
}
void finalize() {
int keyLength = fKey.count();
SkASSERT(0 == (keyLength % 4));
*(this->atOffset<uint32_t, GrProgramDesc::kLengthOffset>()) = SkToU32(keyLength);
uint32_t* checksum = this->atOffset<uint32_t, GrProgramDesc::kChecksumOffset>();
*checksum = 0;
*checksum = SkChecksum::Compute(reinterpret_cast<uint32_t*>(fKey.begin()), keyLength);
}
// The key, stored in fKey, is composed of four parts:
// 1. uint32_t for total key length.
// 2. uint32_t for a checksum.
// 3. Header struct defined above. Also room for extensions to the header
// 4. A Backend specific payload. Room is preallocated for this
enum KeyOffsets {
// Part 1.
kLengthOffset = 0,
// Part 2.
kChecksumOffset = kLengthOffset + sizeof(uint32_t),
// Part 3.
kHeaderOffset = kChecksumOffset + sizeof(uint32_t),
kHeaderSize = SkAlign4(2 * sizeof(KeyHeader)),
};
enum {
kMaxPreallocProcessors = 8,
kIntsPerProcessor = 4, // This is an overestimate of the average effect key size.
kPreAllocSize = kHeaderOffset + kHeaderSize +
kMaxPreallocProcessors * sizeof(uint32_t) * kIntsPerProcessor,
};
SkSTArray<kPreAllocSize, uint8_t, true> fKey;
friend class GrGLProgramDescBuilder;
};
#endif
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