michael@0: 
michael@0: /*
michael@0:  * Copyright 2008 The Android Open Source Project
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  */
michael@0: 
michael@0: 
michael@0: #ifndef SkReader32_DEFINED
michael@0: #define SkReader32_DEFINED
michael@0: 
michael@0: #include "SkMatrix.h"
michael@0: #include "SkPath.h"
michael@0: #include "SkRegion.h"
michael@0: #include "SkRRect.h"
michael@0: #include "SkScalar.h"
michael@0: 
michael@0: class SkString;
michael@0: 
michael@0: class SkReader32 : SkNoncopyable {
michael@0: public:
michael@0:     SkReader32() : fCurr(NULL), fStop(NULL), fBase(NULL) {}
michael@0:     SkReader32(const void* data, size_t size)  {
michael@0:         this->setMemory(data, size);
michael@0:     }
michael@0: 
michael@0:     void setMemory(const void* data, size_t size) {
michael@0:         SkASSERT(ptr_align_4(data));
michael@0:         SkASSERT(SkAlign4(size) == size);
michael@0: 
michael@0:         fBase = fCurr = (const char*)data;
michael@0:         fStop = (const char*)data + size;
michael@0:     }
michael@0: 
michael@0:     uint32_t size() const { return SkToU32(fStop - fBase); }
michael@0:     uint32_t offset() const { return SkToU32(fCurr - fBase); }
michael@0:     bool eof() const { return fCurr >= fStop; }
michael@0:     const void* base() const { return fBase; }
michael@0:     const void* peek() const { return fCurr; }
michael@0: 
michael@0:     uint32_t available() const { return SkToU32(fStop - fCurr); }
michael@0:     bool isAvailable(uint32_t size) const { return fCurr + size <= fStop; }
michael@0: 
michael@0:     void rewind() { fCurr = fBase; }
michael@0: 
michael@0:     void setOffset(size_t offset) {
michael@0:         SkASSERT(SkAlign4(offset) == offset);
michael@0:         SkASSERT(offset <= this->size());
michael@0:         fCurr = fBase + offset;
michael@0:     }
michael@0: 
michael@0:     bool readBool() { return this->readInt() != 0; }
michael@0: 
michael@0:     int32_t readInt() {
michael@0:         SkASSERT(ptr_align_4(fCurr));
michael@0:         int32_t value = *(const int32_t*)fCurr;
michael@0:         fCurr += sizeof(value);
michael@0:         SkASSERT(fCurr <= fStop);
michael@0:         return value;
michael@0:     }
michael@0: 
michael@0:     void* readPtr() {
michael@0:         void* ptr;
michael@0:         // we presume this "if" is resolved at compile-time
michael@0:         if (4 == sizeof(void*)) {
michael@0:             ptr = *(void**)fCurr;
michael@0:         } else {
michael@0:             memcpy(&ptr, fCurr, sizeof(void*));
michael@0:         }
michael@0:         fCurr += sizeof(void*);
michael@0:         return ptr;
michael@0:     }
michael@0: 
michael@0:     SkScalar readScalar() {
michael@0:         SkASSERT(ptr_align_4(fCurr));
michael@0:         SkScalar value = *(const SkScalar*)fCurr;
michael@0:         fCurr += sizeof(value);
michael@0:         SkASSERT(fCurr <= fStop);
michael@0:         return value;
michael@0:     }
michael@0: 
michael@0:     const void* skip(size_t size) {
michael@0:         SkASSERT(ptr_align_4(fCurr));
michael@0:         const void* addr = fCurr;
michael@0:         fCurr += SkAlign4(size);
michael@0:         SkASSERT(fCurr <= fStop);
michael@0:         return addr;
michael@0:     }
michael@0: 
michael@0:     template <typename T> const T& skipT() {
michael@0:         SkASSERT(SkAlign4(sizeof(T)) == sizeof(T));
michael@0:         return *(const T*)this->skip(sizeof(T));
michael@0:     }
michael@0: 
michael@0:     void read(void* dst, size_t size) {
michael@0:         SkASSERT(0 == size || dst != NULL);
michael@0:         SkASSERT(ptr_align_4(fCurr));
michael@0:         memcpy(dst, fCurr, size);
michael@0:         fCurr += SkAlign4(size);
michael@0:         SkASSERT(fCurr <= fStop);
michael@0:     }
michael@0: 
michael@0:     uint8_t readU8() { return (uint8_t)this->readInt(); }
michael@0:     uint16_t readU16() { return (uint16_t)this->readInt(); }
michael@0:     int32_t readS32() { return this->readInt(); }
michael@0:     uint32_t readU32() { return this->readInt(); }
michael@0: 
michael@0:     bool readPath(SkPath* path) {
michael@0:         return readObjectFromMemory(path);
michael@0:     }
michael@0: 
michael@0:     bool readMatrix(SkMatrix* matrix) {
michael@0:         return readObjectFromMemory(matrix);
michael@0:     }
michael@0: 
michael@0:     bool readRRect(SkRRect* rrect) {
michael@0:         return readObjectFromMemory(rrect);
michael@0:     }
michael@0: 
michael@0:     bool readRegion(SkRegion* rgn) {
michael@0:         return readObjectFromMemory(rgn);
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      *  Read the length of a string (written by SkWriter32::writeString) into
michael@0:      *  len (if len is not NULL) and return the null-ternimated address of the
michael@0:      *  string within the reader's buffer.
michael@0:      */
michael@0:     const char* readString(size_t* len = NULL);
michael@0: 
michael@0:     /**
michael@0:      *  Read the string (written by SkWriter32::writeString) and return it in
michael@0:      *  copy (if copy is not null). Return the length of the string.
michael@0:      */
michael@0:     size_t readIntoString(SkString* copy);
michael@0: 
michael@0: private:
michael@0:     template <typename T> bool readObjectFromMemory(T* obj) {
michael@0:         size_t size = obj->readFromMemory(this->peek(), this->available());
michael@0:         // If readFromMemory() fails (which means that available() was too small), it returns 0
michael@0:         bool success = (size > 0) && (size <= this->available()) && (SkAlign4(size) == size);
michael@0:         // In case of failure, we want to skip to the end
michael@0:         (void)this->skip(success ? size : this->available());
michael@0:         return success;
michael@0:     }
michael@0: 
michael@0:     // these are always 4-byte aligned
michael@0:     const char* fCurr;  // current position within buffer
michael@0:     const char* fStop;  // end of buffer
michael@0:     const char* fBase;  // beginning of buffer
michael@0: 
michael@0: #ifdef SK_DEBUG
michael@0:     static bool ptr_align_4(const void* ptr) {
michael@0:         return (((const char*)ptr - (const char*)NULL) & 3) == 0;
michael@0:     }
michael@0: #endif
michael@0: };
michael@0: 
michael@0: #endif