1 // Copyright 2014, ARM Limited 2 // All rights reserved. 3 // 4 // Redistribution and use in source and binary forms, with or without 5 // modification, are permitted provided that the following conditions are met: 6 // 7 // * Redistributions of source code must retain the above copyright notice, 8 // this list of conditions and the following disclaimer. 9 // * Redistributions in binary form must reproduce the above copyright notice, 10 // this list of conditions and the following disclaimer in the documentation 11 // and/or other materials provided with the distribution. 12 // * Neither the name of ARM Limited nor the names of its contributors may be 13 // used to endorse or promote products derived from this software without 14 // specific prior written permission. 15 // 16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS CONTRIBUTORS "AS IS" AND 17 // ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 18 // WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 19 // DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE 20 // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 22 // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 23 // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 25 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 27 #ifndef VIXL_CODE_BUFFER_H 28 #define VIXL_CODE_BUFFER_H 29 30 #include <string.h> 31 #include "vixl/globals.h" 32 33 namespace vixl { 34 35 class CodeBuffer { 36 public: 37 explicit CodeBuffer(size_t capacity = 4 * KBytes); 38 CodeBuffer(void* buffer, size_t capacity); 39 ~CodeBuffer(); 40 41 void Reset(); 42 43 ptrdiff_t OffsetFrom(ptrdiff_t offset) const { 44 ptrdiff_t cursor_offset = cursor_ - buffer_; 45 VIXL_ASSERT((offset >= 0) && (offset <= cursor_offset)); 46 return cursor_offset - offset; 47 } 48 49 ptrdiff_t CursorOffset() const { 50 return OffsetFrom(0); 51 } 52 53 template <typename T> 54 T GetOffsetAddress(ptrdiff_t offset) const { 55 VIXL_ASSERT((offset >= 0) && (offset <= (cursor_ - buffer_))); 56 return reinterpret_cast<T>(buffer_ + offset); 57 } 58 59 size_t RemainingBytes() const { 60 VIXL_ASSERT((cursor_ >= buffer_) && (cursor_ <= (buffer_ + capacity_))); 61 return (buffer_ + capacity_) - cursor_; 62 } 63 64 // A code buffer can emit: 65 // * 32-bit data: instruction and constant. 66 // * 64-bit data: constant. 67 // * string: debug info. 68 void Emit32(uint32_t data) { Emit(data); } 69 70 void Emit64(uint64_t data) { Emit(data); } 71 72 void EmitString(const char* string); 73 74 // Align to kInstructionSize. 75 void Align(); 76 77 size_t capacity() const { return capacity_; } 78 79 bool IsManaged() const { return managed_; } 80 81 void Grow(size_t new_capacity); 82 83 bool IsDirty() const { return dirty_; } 84 85 void SetClean() { dirty_ = false; } 86 87 private: 88 template <typename T> 89 void Emit(T value) { 90 VIXL_ASSERT(RemainingBytes() >= sizeof(value)); 91 dirty_ = true; 92 memcpy(cursor_, &value, sizeof(value)); 93 cursor_ += sizeof(value); 94 } 95 96 // Backing store of the buffer. 97 byte* buffer_; 98 // If true the backing store is allocated and deallocated by the buffer. The 99 // backing store can then grow on demand. If false the backing store is 100 // provided by the user and cannot be resized internally. 101 bool managed_; 102 // Pointer to the next location to be written. 103 byte* cursor_; 104 // True if there has been any write since the buffer was created or cleaned. 105 bool dirty_; 106 // Capacity in bytes of the backing store. 107 size_t capacity_; 108 }; 109 110 } // namespace vixl 111 112 #endif // VIXL_CODE_BUFFER_H 113 114
