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Make pb_decode_varint32 a separate implementation.

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This avoids doing 64-bit arithmetic for 32-bit varint decodings.
It does increase the code size somewhat.

Results for ARM Cortex-M3: -10% execution time, +1% code size, -2% ram usage.
This commit is contained in:
Petteri Aimonen
2013-02-05 22:39:32 +02:00
parent c372ebc665
commit 39b8a5e2bb
1 changed files with 14 additions and 4 deletions
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18
pb_decode.c
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@@ -95,10 +95,20 @@ pb_istream_t pb_istream_from_buffer(uint8_t *buf, size_t bufsize)
static bool checkreturn pb_decode_varint32(pb_istream_t *stream, uint32_t *dest) static bool checkreturn pb_decode_varint32(pb_istream_t *stream, uint32_t *dest)
{ {
uint64_t temp; uint8_t byte;
bool status = pb_decode_varint(stream, &temp); int bitpos = 0;
*dest = (uint32_t)temp; *dest = 0;
return status;
while (bitpos < 32 && pb_read(stream, &byte, 1))
{
*dest |= (uint32_t)(byte & 0x7F) << bitpos;
bitpos += 7;
if (!(byte & 0x80))
return true;
}
PB_RETURN_ERROR(stream, "varint overflow");
} }
bool checkreturn pb_decode_varint(pb_istream_t *stream, uint64_t *dest) bool checkreturn pb_decode_varint(pb_istream_t *stream, uint64_t *dest)