char[] to hex string exercise

Question

Below is my current char* to hex string function. I wrote it as an exercise in bit manipulation. It takes ~7ms on a AMD Athlon MP 2800+ to hexify a 10 million byte array. Is

Answer 1

At the cost of more memory you can create a full 256-entry table of the hex codes:

static const char _hex2asciiU_value[256][2] =
    { {'0','0'}, {'0','1'}, /* ..., */ {'F','E'},{'F','F'} };

Then direct index into the table, no bit fiddling required.

const char *pHexVal = pHex[*pChar];
pszHex[0] = pHexVal[0];
pszHex[1] = pHexVal[1];