[Tarantool-patches] [PATCH v5 2/2] base64: improve decoder performance
Sergey Nikiforov
void at tarantool.org
Fri Dec 25 17:09:07 MSK 2020
Unnecessary checks were removed from internal loops.
Benchmark shows that performance is now ~1.19 times higher
(release build, Intel Core I7-9700K, only one thread).
---
Branch: https://github.com/tarantool/tarantool/tree/void234/gh-3069-fix-base64-memory-overrun-v5
third_party/base64.c | 35 ++++++++++++++++++++++++++---------
1 file changed, 26 insertions(+), 9 deletions(-)
diff --git a/third_party/base64.c b/third_party/base64.c
index 3350a98ff..2b2b61ba4 100644
--- a/third_party/base64.c
+++ b/third_party/base64.c
@@ -257,10 +257,10 @@ base64_decode_block(const char *in_base64, int in_len,
{
case step_a:
do {
- if (in_pos == in_end || out_pos >= out_end)
+ if (in_pos >= in_end)
{
state->step = step_a;
- state->result = curr_byte;
+ /* curr_byte is useless now. */
return out_pos - out_bin;
}
fragment = base64_decode_value(*in_pos++);
@@ -268,7 +268,7 @@ base64_decode_block(const char *in_base64, int in_len,
curr_byte = (fragment & 0x03f) << 2;
case step_b:
do {
- if (in_pos == in_end || out_pos >= out_end)
+ if (in_pos >= in_end)
{
state->step = step_b;
state->result = curr_byte;
@@ -276,14 +276,19 @@ base64_decode_block(const char *in_base64, int in_len,
}
fragment = base64_decode_value(*in_pos++);
} while (fragment < 0);
+ if (out_pos >= out_end)
+ {
+ /* We are losing some data. */
+ state->step = step_b;
+ state->result = curr_byte;
+ return out_pos - out_bin;
+ }
curr_byte |= (fragment & 0x030) >> 4;
*out_pos++ = curr_byte;
curr_byte = (fragment & 0x00f) << 4;
- if (out_pos < out_end)
- *out_pos = curr_byte;
case step_c:
do {
- if (in_pos == in_end || out_pos >= out_end)
+ if (in_pos >= in_end)
{
state->step = step_c;
state->result = curr_byte;
@@ -291,14 +296,19 @@ base64_decode_block(const char *in_base64, int in_len,
}
fragment = base64_decode_value(*in_pos++);
} while (fragment < 0);
+ if (out_pos >= out_end)
+ {
+ /* We are losing some data. */
+ state->step = step_c;
+ state->result = curr_byte;
+ return out_pos - out_bin;
+ }
curr_byte |= (fragment & 0x03c) >> 2;
*out_pos++ = curr_byte;
curr_byte = (fragment & 0x003) << 6;
- if (out_pos < out_end)
- *out_pos = curr_byte;
case step_d:
do {
- if (in_pos == in_end || out_pos >= out_end)
+ if (in_pos >= in_end)
{
state->step = step_d;
state->result = curr_byte;
@@ -306,6 +316,13 @@ base64_decode_block(const char *in_base64, int in_len,
}
fragment = base64_decode_value(*in_pos++);
} while (fragment < 0);
+ if (out_pos >= out_end)
+ {
+ /* We are losing some data. */
+ state->step = step_d;
+ state->result = curr_byte;
+ return out_pos - out_bin;
+ }
curr_byte |= (fragment & 0x03f);
*out_pos++ = curr_byte;
}
--
2.25.1
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