// Copyright 2006 The Android Open Source Project #include #include #include #include #include "decoder.h" #include "trace_common.h" // This array provides a fast conversion from the initial byte in // a varint-encoded object to the length (in bytes) of that object. int prefix_to_len[] = { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 9, 9, 17, 17 }; // This array provides a fast conversion from the initial byte in // a varint-encoded object to the initial data bits for that object. int prefix_to_data[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 0, 1, 2, 3, 4, 5, 6, 7, 0, 1, 2, 3, 0, 0, 0, 0 }; signed char prefix_to_signed_data[] = { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf, 0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf, 0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef, 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef, 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff, 0x00, 0x01, 0x02, 0x03, 0xfc, 0xfd, 0xfe, 0xff, 0x00, 0x01, 0xfe, 0xff, 0x00, 0xff, 0x00, 0xff, }; Decoder::Decoder() { filename_ = NULL; fstream_ = NULL; next_ = NULL; end_ = NULL; } Decoder::~Decoder() { Close(); delete[] filename_; } void Decoder::Close() { if (fstream_) { fclose(fstream_); fstream_ = NULL; } } void Decoder::Open(char *filename) { if (filename_ != NULL) { delete[] filename_; } filename_ = new char[strlen(filename) + 1]; strcpy(filename_, filename); fstream_ = fopen(filename_, "r"); if (fstream_ == NULL) { perror(filename_); exit(1); } int rval = fread(buf_, 1, kBufSize, fstream_); if (rval != kBufSize) { if (ferror(fstream_)) { perror(filename_); exit(1); } if (!feof(fstream_)) { fprintf(stderr, "Unexpected short fread() before eof\n"); exit(1); } } next_ = buf_; end_ = buf_ + rval; } void Decoder::FillBuffer() { assert(next_ <= end_); if (end_ - next_ < kDecodingSpace && end_ == &buf_[kBufSize]) { // Copy the unused bytes left at the end to the beginning of the // buffer. int len = end_ - next_; if (len > 0) memcpy(buf_, next_, len); // Read enough bytes to fill up the buffer, if possible. int nbytes = kBufSize - len; int rval = fread(buf_ + len, 1, nbytes, fstream_); if (rval < nbytes) { if (ferror(fstream_)) { perror(filename_); exit(1); } if (!feof(fstream_)) { fprintf(stderr, "Unexpected short fread() before eof\n"); exit(1); } } end_ = &buf_[len + rval]; next_ = buf_; } } void Decoder::Read(char *dest, int len) { while (len > 0) { int nbytes = end_ - next_; if (nbytes == 0) { FillBuffer(); nbytes = end_ - next_; if (nbytes == 0) break; } if (nbytes > len) nbytes = len; memcpy(dest, next_, nbytes); dest += nbytes; len -= nbytes; next_ += nbytes; } } // Decode a varint-encoded object starting at the current position in // the array "buf_" and return the decoded value as a 64-bit integer. // A varint-encoded object has an initial prefix that specifies how many // data bits follow. If the first bit is zero, for example, then there // are 7 data bits that follow. The table below shows the prefix values // and corresponding data bits. // // Prefix Bytes Data bits // 0 1 7 // 10 2 14 // 110 3 21 // 1110 4 28 // 11110 5 35 // 111110 6 42 // 11111100 9 64 // 11111101 reserved // 11111110 reserved // 11111111 reserved int64_t Decoder::Decode(bool is_signed) { int64_t val64; if (end_ - next_ < kDecodingSpace) FillBuffer(); #if BYTE_ORDER == BIG_ENDIAN uint8_t byte0 = *next_; // Get the number of bytes to decode based on the first byte. int len = prefix_to_len[byte0]; if (next_ + len > end_) { fprintf(stderr, "%s: decoding past end of file.\n", filename_); exit(1); } // Get the first data byte. if (is_signed) val64 = prefix_to_signed_data[byte0]; else val64 = prefix_to_data[byte0]; next_ += 1; for (int ii = 1; ii < len; ++ii) { val64 = (val64 << 8) | *next_++; } #else // If we are on a little-endian machine, then use large, unaligned loads. uint64_t data = *(reinterpret_cast(next_)); uint8_t byte0 = data; data = bswap64(data); // Get the number of bytes to decode based on the first byte. int len = prefix_to_len[byte0]; if (next_ + len > end_) { fprintf(stderr, "%s: decoding past end of file.\n", filename_); exit(1); } // Get the first data byte. if (is_signed) val64 = prefix_to_signed_data[byte0]; else val64 = prefix_to_data[byte0]; switch (len) { case 1: break; case 2: val64 = (val64 << 8) | ((data >> 48) & 0xffull); break; case 3: val64 = (val64 << 16) | ((data >> 40) & 0xffffull); break; case 4: val64 = (val64 << 24) | ((data >> 32) & 0xffffffull); break; case 5: val64 = (val64 << 32) | ((data >> 24) & 0xffffffffull); break; case 6: val64 = (val64 << 40) | ((data >> 16) & 0xffffffffffull); break; case 9: data = *(reinterpret_cast(&next_[1])); val64 = bswap64(data); break; } next_ += len; #endif return val64; }