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yas源码解析之 hexdump打印二进制

news 来源：原创 2024/9/20 9:35:22

概述

“hexdump”就是一种用于以十六进制格式显示文件或数据内容的工具或操作。它能够将数据转换为十六进制的数字形式，并以特定的格式展示出来，以便于对数据进行分析和检查。

相信使用过UltraEdit查看二进制文件的同学都非常熟悉类似下面的内容：

0000000: 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................
0000016: 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f |................
0000032: 20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f | !"#$%&'()*+,-./
0000048: 30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f |0123456789:;<=>?
0000064: 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f |@ABCDEFGHIJKLMNO
0000080: 50 51 52 53 54 55 56 57 58 59 5a 5b 5c 5d 5e 5f |PQRSTUVWXYZ[\]^_
0000096: 60 61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f |`abcdefghijklmno
0000112: 70 71 72 73 74 75 76 77 78 79 7a 7b 7c 7d 7e 7f |pqrstuvwxyz{|}~.

最左侧是地址，中间16进制部分为二进制数据的16进制表示，最右侧为二进制数据ascii码表示。

如果，我们想将平时我们工程实践中的二进制数据进行hexdump怎么办？重新造轮子？现在恭喜你，yas已经帮你造好了。

yas中hexdump的实现

hexdump的实现代码在hexdump.hpp中，所有的代码如下：

#ifndef __yas__tools__hexdump_hpp
#define __yas__tools__hexdump_hpp#include <yas/detail/tools/cast.hpp>
#include <yas/buffers.hpp>#include <sstream>
#include <iomanip>namespace yas {
namespace detail {/***************************************************************************/inline std::size_t chksum_crc32(const void *ptr, std::size_t length) {static const std::uint32_t crc32_table[] = {0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA,0x076DC419, 0x706AF48F, 0xE963A535, 0x9E6495A3,0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988,0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91,0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE,0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7,0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC,0x14015C4F, 0x63066CD9, 0xFA0F3D63, 0x8D080DF5,0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172,0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B,0x35B5A8FA, 0x42B2986C, 0xDBBBC9D6, 0xACBCF940,0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59,0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116,0x21B4F4B5, 0x56B3C423, 0xCFBA9599, 0xB8BDA50F,0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924,0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D,0x76DC4190, 0x01DB7106, 0x98D220BC, 0xEFD5102A,0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433,0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818,0x7F6A0DBB, 0x086D3D2D, 0x91646C97, 0xE6635C01,0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E,0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457,0x65B0D9C6, 0x12B7E950, 0x8BBEB8EA, 0xFCB9887C,0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65,0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2,0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB,0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0,0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9,0x5005713C, 0x270241AA, 0xBE0B1010, 0xC90C2086,0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F,0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4,0x59B33D17, 0x2EB40D81, 0xB7BD5C3B, 0xC0BA6CAD,0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A,0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683,0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8,0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1,0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE,0xF762575D, 0x806567CB, 0x196C3671, 0x6E6B06E7,0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC,0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5,0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4, 0x4FDFF252,0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B,0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60,0xDF60EFC3, 0xA867DF55, 0x316E8EEF, 0x4669BE79,0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236,0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F,0xC5BA3BBE, 0xB2BD0B28, 0x2BB45A92, 0x5CB36A04,0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D,0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A,0x9C0906A9, 0xEB0E363F, 0x72076785, 0x05005713,0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38,0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21,0x86D3D2D4, 0xF1D4E242, 0x68DDB3F8, 0x1FDA836E,0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777,0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C,0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45,0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2,0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB,0xAED16A4A, 0xD9D65ADC, 0x40DF0B66, 0x37D83BF0,0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9,0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6,0xBAD03605, 0xCDD70693, 0x54DE5729, 0x23D967BF,0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94,0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D};std::size_t crc = 0xFFFFFFFF;const std::uint8_t *block = static_cast<const std::uint8_t*>(ptr);for ( std::size_t idx = 0; idx < length; ++idx ) {crc = ((crc >> 8) & 0x00FFFFFF) ^ crc32_table[(crc ^ *block++) & 0xFF];}return (crc ^ 0xFFFFFFFF);
}} // namespace detail/***************************************************************************/inline std::ostream& hexdump(std::ostream &os, const void *buf, std::size_t len) {if ( !buf || !len ) return os;std::ios::fmtflags fmt(os.flags());const std::uint8_t *buffer = static_cast<const std::uint8_t*>(buf);// addr: 内存地址，假设buffer的开头地址为0// n: buffer中字符的位置索引// idx：当前行待打印的buffer字符的位置索引// cnt2：当前行打印的字符总数std::size_t addr = 0, n = 0, idx = 0, cnt2 = 0;for ( n = 0; n < len; ++n ) {if ( cnt2 == 0 ) {// 打印地址os << std::setw(7) << std::setfill('0') << addr << ": ";// 16：表示每行打印buf中的16个字节addr += 16;}cnt2 = (cnt2 + 1) % 18;if ( cnt2 <= 16 ) {os << std::hex << std::setw(2) << std::setfill('0') << __YAS_SCAST(std::size_t, buffer[n]) << ' ';} else {os << '|';// 设置填充字符为空格os << std::setfill(' ');for ( idx = n - cnt2 + 1; idx < n; ++idx) {// 注：ascii码小于32和大于126的，为不可打印的字符if ( buffer[idx] < 32 || 126 < buffer[idx] ) {os << '.';} else {os << buffer[idx];}}os << std::endl << std::dec;cnt2 = 0;n--;}}os << std::setfill(' ');// 最后一行不足16个字节时，16进制使用“--”代替for ( idx = cnt2+1; idx <= 16 ; ++idx ) {os << std::setw(2) << "-- ";}os << '|';for ( idx = n-cnt2; cnt2 <= 16 && idx < n; ++idx ) {if ( buffer[idx] < 32 || 126 < buffer[idx] ) {os << '.';} else {os << buffer[idx];}}// 后续通过该输出流输出的数据将以十进制的形式呈现os << std::dec;// 输出总字节数和crc校验码os << std::endl<< "LEN  : " << len << " bytes, "<< "CRC32: 0x" << std::hex << detail::chksum_crc32(buf, len);os.flags(fmt);return os;
}inline std::ostream& hexdump(std::ostream &os, const intrusive_buffer &buf) {return hexdump(os, buf.data, buf.size);
}inline std::ostream& hexdump(std::ostream &os, const shared_buffer &buf) {return hexdump(os, buf.data.get(), buf.size);
}inline std::string hexdump(const void *ptr, std::size_t size) {std::ostringstream os;hexdump(os, ptr, size);return os.str();
}inline std::string hexdump(const intrusive_buffer &buf) {return hexdump(buf.data, buf.size);
}inline std::string hexdump(const shared_buffer &buf) {return hexdump(buf.data.get(), buf.size);
}/***************************************************************************/} // namespace yas#endif // __yas__tools__hexdump_hpp

hexdump打印的核心代码的实现逻辑，已经进行了注释，大家直接看上面的代码就可以了。

关于CRC32校验码的生成逻辑，我就不解释了，我也看不懂，就当初固定实现就行了，拿来直接用就可以。

下面对其使用方法进行简单介绍。

示例代码

代码的解释已经放在代码中了，不做过多说明了。

// 定义nums变量，每个元素为一个ascii字符
std::vector<unsigned char> nums(128);
for (size_t i = 0; i < 128; i++)
{nums[i] = i;
}// 直接hexdump到控制台
yas::hexdump(std::cout, &nums[0], sizeof(unsigned char) * nums.size());
std::cout << std::endl;// 将hexdump后得到字符串赋值给hexstr后，再进行打印
std::string hexstr = yas::hexdump(&nums[0], sizeof(unsigned char) * nums.size());
std::cout << hexstr << std::endl;