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我想生成一个 Eisa 3 chars Id，但似乎我太累了，看不出我到底在哪里搞砸了..加上 js 中的位移或其他任何东西还不是我最喜欢的茶；）

有人感兴趣吗？:)

看来我需要添加更多细节：我目前正在使用 vim 和 xxd 玩弄 EDID .bin，现在我在校验和方面得到了很好的东西（还没有在 js 中）和保存那个.bin，我想尝试通过编写基于Web的EDID修改工具来构建dgallegos的工作（至少为制造商、序列号等生成正确的十六进制......）

nb：非常感谢 dgallegos 的基于 Web 的 EDID 阅读器；）

var getEisaId = function()
{
  var FIVE_BIT_LETTER_MASK = 0x1F;
  var EISA_ID_BYTE1 = 8;
  var EISA_ID_BYTE2 = 9;
  var EISA_LETTER1_OFF = 2
  var EISA_LETTER2_OFF = 5;
  var LETTER2_TOP_BYTES = 3;
  var LETTER2_TOP_MASK = 0x03;
  var LETTER2_BOT_MASK = 0x07;

  var firstLetter = (0xA1 >> EISA_LETTER1_OFF) &
                                            FIVE_BIT_LETTER_MASK;

  // Get the first two bits [2:0] of the top byte
  var secondLetterTop = 0xA1 & LETTER2_TOP_MASK;
  // Get the last three bits [7:5] of the bottom byte
  var secondLetterBottom = (0x00 >> EISA_LETTER2_OFF) &
                                            LETTER2_BOT_MASK;
  // Combine the top and bottom
  var secondLetter = (secondLetterTop << LETTER2_TOP_BYTES) | secondLetterBottom;

  var thirdLetter = 0x00 & FIVE_BIT_LETTER_MASK;

  return intToAscii(firstLetter)+intToAscii(secondLetter)+intToAscii(thirdLetter);
}

function intToAscii(intCode)
{
    var abc = "0ABCDEFGHIJKLMNOPQRSTUVWXYZ".split("");
    return abc[intCode];
}

getEisaId();


/* ====  this is fine ;p ====*/
function asciiToInt(asciiChar){
  return "0ABCDEFGHIJKLMNOPQRSTUVWXYZ".indexOf(asciiChar);
}
//var byte9 = ( asciiToInt("0").toString(2) & 0x1F ).toString(16)

/* ====  this is not yet aside for "HHH" :/ ====*/
var generateEisaId = function(threeCharsId){
  var FIVE_BIT_LETTER_MASK = 0x1F;
  var EISA_LETTER1_OFF = 2;
  var EISA_LETTER2_OFF = 5;
  var LETTER2_TOP_BYTES = 3;
  var LETTER2_TOP_MASK = 0x03;
  var LETTER2_BOT_MASK = 0x07; // 111 in base 2

  var charsArr = threeCharsId.split('').splice(0, 3); // delete anything after 3rd char
  
  // format 1st char
  var firstLetterBin = asciiToInt(charsArr[0]); //.toString(2); // get index from letter, and get its binary representation
  console.log('1st letter: ' + charsArr[0] + ' > ' + asciiToInt(charsArr[0]) + ' (int/base10) > ' + firstLetterBin.toString(2) + ' (bin/base2)');

  // format 2nd char
  var secondLetterBin = asciiToInt(charsArr[1]); //.toString(2);
  console.log('2nd letter: ' + charsArr[1] + ' > ' + asciiToInt(charsArr[1]) + ' (int/base10) > ' + secondLetterBin.toString(2) + ' (bin/base2)');
  // get the second letter binary chunk for the 1st two bits of the top byte
  //var secondLetterTopBin = secondLetterBin >> LETTER2_TOP_MASK;
  //var secondLetterTopBin = secondLetterBin & LETTER2_TOP_MASK;
  //var secondLetterTopBin = secondLetterBin & LETTER2_TOP_MASK;
  var secondLetterTopBin = secondLetterBin >> 3; // shift 3 positions right ( drop stuff )
  console.log('2nd letter top bin: ' + secondLetterTopBin.toString(2));

  // get the second letter binary chunk for the last three bits of the bottom byte
  //var secondLetterBottomBin = secondLetterBin & LETTER2_BOT_MASK;
  var secondLetterBottomBin = ( secondLetterBin << 2 ) & 0x07;
  console.log('2nd letter bottom bin: ' + secondLetterBottomBin.toString(2));

  // format Last char
  var thirdLetterBin = asciiToInt(charsArr[2]); //.toString(2);
  console.log('3rd letter: ' + charsArr[2] + ' > ' + asciiToInt(charsArr[2]) + ' (int/base10) > ' + thirdLetterBin.toString(2) + ' (bin/base2)');

  // 1st byte - add 1st char binary to top byte & shift it 2 positions left to make room for 2nd char 1st binary chunk of 2 bits
  var firstLetterOnceOffset = ( firstLetterBin << EISA_LETTER1_OFF ) & FIVE_BIT_LETTER_MASK;
  //var firstLetterOnceOffset = ( firstLetterBin & 0xA0 );

  console.log('1st letter once offset: ' + firstLetterOnceOffset.toString(2));
  //var topByte = ( ( firstLetterBin << EISA_LETTER1_OFF ) | secondLetterTopBin ) >> 2;
  var topByte = ( firstLetterBin << EISA_LETTER1_OFF ) | secondLetterTopBin;
  console.log('top byte: ' + topByte.toString(2) );

  // 2nd byte - add 3rd char binary to bottom byte & shift it 3 positions right to make room for 2nd char 2nd binary chunk of 3 bits
  //var bottomByte = ( thirdLetterBin & FIVE_BIT_LETTER_MASK ) | ( secondLetterBottomBin << EISA_LETTER2_OFF )
  //var bottomByte = ( thirdLetterBin & FIVE_BIT_LETTER_MASK ) | ( secondLetterBottomBin << EISA_LETTER2_OFF );
  //var bottomByte = ( thirdLetterBin & FIVE_BIT_LETTER_MASK );
  var bottomByte = thirdLetterBin | ( secondLetterBottomBin << EISA_LETTER2_OFF ); // & 0xA0;
  //var bottomByte = ( thirdLetterBin & FIVE_BIT_LETTER_MASK ) | ( secondLetterBottomBin << 8 );
  //var bottomByte = ( thirdLetterBin & FIVE_BIT_LETTER_MASK ) | ( secondLetterBottomBin << 8 ); // &0x1F;
  console.log('bottom byte: ' + bottomByte.toString(2));

  // padding ? 
  var n1 = topByte.toString(2);
  n1 = "00000000".substr(n1.length) + n1;
  console.log('padded top byte: ' + n1);
  var n2 = bottomByte.toString(2);
  n2 = "00000000".substr(n2.length) + n2;
  console.log('padded bottom byte: ' + n2);
  
  // get hex's of the padded versions ?
  var eisaIdP = '0x' + parseInt(n1, 2).toString(16) + ' 0x' + parseInt(n2, 2).toString(16);
  console.log('padded: ' + eisaIdP);

  // get hex's for both of the aboves
  var eisaId = '0x' + topByte.toString(16) + bottomByte.toString(16);
  return eisaId;

}
var myId = generateEisaId('HHH');
var myId = generateEisaId('AAA');
console.log('generated Eisa Id hex: ' + myId);

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1 回答 1

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好吧，睡了一会儿，回头看看那些东西，“它变得清晰了”；）

对于一点背景，3 个字母被分成 2 个字节。我们有一个索引字母的“字典”作为整数数组。从存储索引的数组的长度中，我们知道每个字母的可用位最大为 5 位（如果我们要将这 3 个字母存储在上述 2 个字节中，这会在第一个字节上给我们一个未设置的位），因为用作“字典”中最后一个字符的索引的整数在一个字节中占用 5 位（因此被认为是最大值）

因此，试图让字母 'Z' 显示 3 次（所以 'ZZZ' ）将导致以下过程：

/*
  Z -> 26    (dec/base10)
       0x1A  (hex/base16)
       11010 ( bin/base2)

  Z:              11010
  padded Z:    00011010
  bytes:       00000000 | 00000000
  split:     0 00000 00 | 000 00000
  result:    0 11010 11 | 010 11010
  formatted:   01101011 | 01011010
  hex:             0x6b | 0x5a
  -> SUCCESS! ==> gives us 'ZZZ'
*/

任何有一点点颜色的东西都更清晰（至少对我而言），以下内容确实很有帮助（但没​​有突出显示“在两位操作之间丢失 0”.. 吗？..）

R：检查实际的浏览器控制台；）

var logBits = function(num, showHex){
  var numBits = num.toString(2);
  //var prefixLen = 8 - numBits;
  var prefixStr = '';
  //console.log(8 - numBits.length);
  for(var i=0; i< 8 - numBits.length; i++){ prefixStr +='0'; }
  if(showHex === true) console.log('0b%c' + prefixStr + '%c' + numBits + ' 0x' + num.toString(16), 'color: blue;', 'color: black;');
  else console.log('0b%c' + prefixStr + '%c' + numBits, 'color: blue;', 'color: black;');
}
// to do: alternate version that colors in other color ( or doesn't color at all )
// "leading zeros that were lost we manipulating bits" to better perceive the changes in logs

// usage:
logBits(26);

上面写好了，接下来就是：

// helper
function asciiToInt(asciiChar){
  return "0ABCDEFGHIJKLMNOPQRSTUVWXYZ".indexOf(asciiChar);
}

var genEisaId = function(threeCharsId, arr){
  var charsArr = threeCharsId.split('').splice(0, 3); // delete anything after 3rd char
  
  // get mapping idx's
  var firstLetterBin = asciiToInt(charsArr[0]);
  var secondLetterBin = asciiToInt(charsArr[1]);
  var thirdLetterBin = asciiToInt(charsArr[2]);
  
  // process
  var secondLetter1stChunk = secondLetterBin >> 3; // discard the three last bits
  var secondLetter2ndChunk = secondLetterBin & 0x07; //0b00111; // gets only the three last bits
  
  // build
  var firstByte = (firstLetterBin << 2 ) | secondLetter1stChunk;
  var secondByte = (secondLetter2ndChunk << 5) | thirdLetterBin;
  
  // post-proc
  //var firstByteHex = firstByte.toString(16);
  //var secondByteHex = secondByte.toString(16);
  var firstByteHex = (firstByte.toString(16).length == 2 )? firstByte.toString(16) : '0' + firstByte.toString(16);
  var secondByteHex = (secondByte.toString(16).length == 2) ? secondByte.toString(16) : '0' + secondByte.toString(16);
  
  // return hex's
  if(arr === true) return['0x' + firstByteHex, '0x' + secondByteHex];
  else return '0x' + firstByteHex + ' 0x' + secondByteHex;
}

// usage:
console.log ( genEisaId('TEF') )

当给定一串字符时，上述函数将很乐意生成任何 3 个字母的 EISA ID 十六进制（如果太长，可能会丢弃一些字符；））

再次感谢@dgallegos 在http://www.edidreader.com/上的工作并在 github 上分享（通过深入研究“getEisaId()”和“intToAscii”获得映射和解码的基础，帮助很大）。

我希望发布'将帮助其他人生成一个 ID 或发现他有用的工具:)

于 2018-07-16T20:04:25.880 回答