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Diffstat (limited to 'emulator/qtools/decoder.cpp')
| -rw-r--r-- | emulator/qtools/decoder.cpp | 278 |
1 files changed, 278 insertions, 0 deletions
diff --git a/emulator/qtools/decoder.cpp b/emulator/qtools/decoder.cpp new file mode 100644 index 0000000..ec53181 --- /dev/null +++ b/emulator/qtools/decoder.cpp @@ -0,0 +1,278 @@ +// Copyright 2006 The Android Open Source Project + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <assert.h> +#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<uint64_t*>(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<uint64_t*>(&next_[1])); + val64 = bswap64(data); + break; + } + next_ += len; +#endif + return val64; +} |