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src: remove unnecessary calculation in base64.h #33839

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src: remove unnecessary calculation in base64.h #33839

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66 changes: 26 additions & 40 deletions src/base64.h
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Original file line number Diff line number Diff line change
Expand Up @@ -11,37 +11,26 @@
namespace node {
//// Base 64 ////
static inline constexpr size_t base64_encoded_size(size_t size) {
return ((size + 2 - ((size + 2) % 3)) / 3 * 4);
return ((size + 2) / 3 * 4);
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}

// Doesn't check for padding at the end. Can be 1-2 bytes over.
static inline size_t base64_decoded_size_fast(size_t size) {
size_t remainder = size % 4;

size = (size / 4) * 3;
if (remainder) {
if (size == 0 && remainder == 1) {
// special case: 1-byte input cannot be decoded
size = 0;
} else {
// non-padded input, add 1 or 2 extra bytes
size += 1 + (remainder == 3);
}
}

return size;
static inline constexpr size_t base64_decoded_size_fast(size_t size) {
// 1-byte input cannot be decoded
return size > 1 ? (size / 4) * 3 + (size % 4 + 1) / 2 : 0;
}

template <typename TypeName>
size_t base64_decoded_size(const TypeName* src, size_t size) {
if (size == 0)
// 1-byte input cannot be decoded
if (size < 2)
return 0;

if (src[size - 1] == '=')
if (src[size - 1] == '=') {
size--;
if (size > 0 && src[size - 1] == '=')
size--;

if (src[size - 1] == '=')
size--;
}
return base64_decoded_size_fast(size);
}

Expand Down Expand Up @@ -166,25 +155,22 @@ static size_t base64_encode(const char* src,
k += 4;
}

if (n != slen) {
switch (slen - n) {
case 1:
a = src[i + 0] & 0xff;
dst[k + 0] = table[a >> 2];
dst[k + 1] = table[(a & 3) << 4];
dst[k + 2] = '=';
dst[k + 3] = '=';
break;

case 2:
a = src[i + 0] & 0xff;
b = src[i + 1] & 0xff;
dst[k + 0] = table[a >> 2];
dst[k + 1] = table[((a & 3) << 4) | (b >> 4)];
dst[k + 2] = table[(b & 0x0f) << 2];
dst[k + 3] = '=';
break;
}
switch (slen - n) {
case 1:
a = src[i + 0] & 0xff;
dst[k + 0] = table[a >> 2];
dst[k + 1] = table[(a & 3) << 4];
dst[k + 2] = '=';
dst[k + 3] = '=';
break;
case 2:
a = src[i + 0] & 0xff;
b = src[i + 1] & 0xff;
dst[k + 0] = table[a >> 2];
dst[k + 1] = table[((a & 3) << 4) | (b >> 4)];
dst[k + 2] = table[(b & 0x0f) << 2];
dst[k + 3] = '=';
break;
}

return dlen;
Expand Down