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authorPetteri Aimonen <jpa@git.mail.kapsi.fi>2013-02-06 22:11:02 +0200
committerPetteri Aimonen <jpa@git.mail.kapsi.fi>2013-02-06 22:11:02 +0200
commit4f379364b31fd608f531290e7fb126870769df97 (patch)
tree37341e53f84b6fa985595f45ed29e9dc14bed619 /pb_decode.c
parentd23939d688b36bf9b474ab9077d4a42b69b8442d (diff)
Improve the pb_decode_varint implementations.
Results for ARM: -4% execution time, +1% code size
Diffstat (limited to 'pb_decode.c')
-rw-r--r--pb_decode.c58
1 files changed, 40 insertions, 18 deletions
diff --git a/pb_decode.c b/pb_decode.c
index 7c3407ce..51df32f8 100644
--- a/pb_decode.c
+++ b/pb_decode.c
@@ -107,37 +107,59 @@ 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)
{
uint8_t byte;
- int bitpos = 0;
- *dest = 0;
+ uint32_t result;
+
+ if (!pb_read(stream, &byte, 1))
+ return false;
- while (bitpos < 32 && pb_read(stream, &byte, 1))
+ if (!(byte & 0x80))
{
- *dest |= (uint32_t)(byte & 0x7F) << bitpos;
- bitpos += 7;
-
- if (!(byte & 0x80))
- return true;
+ /* Quick case, 1 byte value */
+ result = byte;
}
-
- PB_RETURN_ERROR(stream, "varint overflow");
+ else
+ {
+ /* Multibyte case */
+ int bitpos = 7;
+ result = byte & 0x7F;
+
+ do
+ {
+ if (bitpos >= 32)
+ PB_RETURN_ERROR(stream, "varint overflow");
+
+ if (!pb_read(stream, &byte, 1))
+ return false;
+
+ result |= (uint32_t)(byte & 0x7F) << bitpos;
+ bitpos += 7;
+ } while (byte & 0x80);
+ }
+
+ *dest = result;
+ return true;
}
bool checkreturn pb_decode_varint(pb_istream_t *stream, uint64_t *dest)
{
uint8_t byte;
int bitpos = 0;
- *dest = 0;
+ uint64_t result = 0;
- while (bitpos < 64 && pb_read(stream, &byte, 1))
+ do
{
- *dest |= (uint64_t)(byte & 0x7F) << bitpos;
- bitpos += 7;
+ if (bitpos >= 64)
+ PB_RETURN_ERROR(stream, "varint overflow");
- if (!(byte & 0x80))
- return true;
- }
+ if (!pb_read(stream, &byte, 1))
+ return false;
+
+ result |= (uint64_t)(byte & 0x7F) << bitpos;
+ bitpos += 7;
+ } while (byte & 0x80);
- PB_RETURN_ERROR(stream, "varint overflow");
+ *dest = result;
+ return true;
}
bool checkreturn pb_skip_varint(pb_istream_t *stream)