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base64: encode without snprintf: a 29x speedup #10026

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base64: encode without snprintf: a 29x speedup #10026

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6412f97
base64: encode without using snprintf
bagder Dec 3, 2022
7ff5ed5
fixup remove the obuf
bagder Dec 4, 2022
b8a0f1f
fixup remove the assign all together
bagder Dec 4, 2022
cfd70dc
fixup loop through all the 3-bytes combos first
bagder Dec 4, 2022
a0a7454
fixup loop counter
bagder Dec 4, 2022
b795057
fixup simplify the trailer part
bagder Dec 4, 2022
0ef7979
fixup remove curl_prinft.h incldue file
bagder Dec 5, 2022
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43 changes: 19 additions & 24 deletions lib/base64.c
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Original file line number Diff line number Diff line change
Expand Up @@ -196,9 +196,9 @@ static CURLcode base64_encode(const char *table64,
if(!output)
return CURLE_OUT_OF_MEMORY;

while(insize > 0) {
while(insize) {
for(i = inputparts = 0; i < 3; i++) {
if(insize > 0) {
if(insize) {
inputparts++;
ibuf[i] = (unsigned char) *indata;
indata++;
Expand All @@ -208,39 +208,34 @@ static CURLcode base64_encode(const char *table64,
ibuf[i] = 0;
}

obuf[0] = (unsigned char) ((ibuf[0] & 0xFC) >> 2);
obuf[1] = (unsigned char) (((ibuf[0] & 0x03) << 4) | \
((ibuf[1] & 0xF0) >> 4));
obuf[2] = (unsigned char) (((ibuf[1] & 0x0F) << 2) | \
((ibuf[2] & 0xC0) >> 6));
obuf[3] = (unsigned char) (ibuf[2] & 0x3F);
obuf[0] = ibuf[0] >> 2;
obuf[1] = (((ibuf[0] & 0x03) << 4) | ((ibuf[1] & 0xF0) >> 4));

*output++ = table64[obuf[0]];
*output++ = table64[obuf[1]];

switch(inputparts) {
case 1: /* only one byte read */
i = msnprintf(output, 5, "%c%c%s%s",
table64[obuf[0]],
table64[obuf[1]],
padstr,
padstr);
if(*padstr) {
*output++ = *padstr;
*output++ = *padstr;
}
break;

case 2: /* two bytes read */
i = msnprintf(output, 5, "%c%c%c%s",
table64[obuf[0]],
table64[obuf[1]],
table64[obuf[2]],
padstr);
obuf[2] = (((ibuf[1] & 0x0F) << 2) | ((ibuf[2] & 0xC0) >> 6));
*output++ = table64[obuf[2]];
if(*padstr)
*output++ = *padstr;
break;

default:
i = msnprintf(output, 5, "%c%c%c%c",
table64[obuf[0]],
table64[obuf[1]],
table64[obuf[2]],
table64[obuf[3]]);
obuf[2] = (((ibuf[1] & 0x0F) << 2) | ((ibuf[2] & 0xC0) >> 6));
obuf[3] = ibuf[2] & 0x3F;
*output++ = table64[obuf[2]];
*output++ = table64[obuf[3]];
break;
}
output += i;
}

/* Zero terminate */
Expand Down