Process data in chunks of four or eight bytes, depending on host, instead of
one at a time.
before:
55561 decicycles in av_aes_ctr_crypt
after:
52204 decicycles in av_aes_ctr_crypt
Signed-off-by: James Almer <jamr...@gmail.com>
---
libavutil/aes_ctr.c | 47 ++++++++++++++++++++-------------------------
1 file changed, 21 insertions(+), 26 deletions(-)
diff --git a/libavutil/aes_ctr.c b/libavutil/aes_ctr.c
index c2d6d570e7..d720aa6aaf 100644
--- a/libavutil/aes_ctr.c
+++ b/libavutil/aes_ctr.c
@@ -24,6 +24,7 @@
#include "aes_ctr.h"
#include "aes.h"
#include "aes_internal.h"
+#include "intreadwrite.h"
#include "macros.h"
#include "mem.h"
#include "random_seed.h"
@@ -32,8 +33,7 @@
typedef struct AVAESCTR {
uint8_t counter[AES_BLOCK_SIZE];
- uint8_t encrypted_counter[AES_BLOCK_SIZE];
- int block_offset;
+ DECLARE_ALIGNED(8, uint8_t, encrypted_counter)[AES_BLOCK_SIZE];
AVAES aes;
} AVAESCTR;
@@ -46,13 +46,11 @@ void av_aes_ctr_set_iv(struct AVAESCTR *a, const uint8_t*
iv)
{
memcpy(a->counter, iv, AES_CTR_IV_SIZE);
memset(a->counter + AES_CTR_IV_SIZE, 0, sizeof(a->counter) -
AES_CTR_IV_SIZE);
- a->block_offset = 0;
}
void av_aes_ctr_set_full_iv(struct AVAESCTR *a, const uint8_t* iv)
{
memcpy(a->counter, iv, sizeof(a->counter));
- a->block_offset = 0;
}
const uint8_t* av_aes_ctr_get_iv(struct AVAESCTR *a)
@@ -75,7 +73,6 @@ int av_aes_ctr_init(struct AVAESCTR *a, const uint8_t *key)
av_aes_init(&a->aes, key, 128, 0);
memset(a->counter, 0, sizeof(a->counter));
- a->block_offset = 0;
return 0;
}
@@ -101,31 +98,29 @@ void av_aes_ctr_increment_iv(struct AVAESCTR *a)
{
av_aes_ctr_increment_be64(a->counter);
memset(a->counter + AES_CTR_IV_SIZE, 0, sizeof(a->counter) -
AES_CTR_IV_SIZE);
- a->block_offset = 0;
}
void av_aes_ctr_crypt(struct AVAESCTR *a, uint8_t *dst, const uint8_t *src,
int count)
{
- const uint8_t* src_end = src + count;
- const uint8_t* cur_end_pos;
- uint8_t* encrypted_counter_pos;
-
- while (src < src_end) {
- if (a->block_offset == 0) {
- av_aes_crypt(&a->aes, a->encrypted_counter, a->counter, 1, NULL,
0);
-
- av_aes_ctr_increment_be64(a->counter + 8);
- }
-
- encrypted_counter_pos = a->encrypted_counter + a->block_offset;
- cur_end_pos = src + AES_BLOCK_SIZE - a->block_offset;
- cur_end_pos = FFMIN(cur_end_pos, src_end);
-
- a->block_offset += cur_end_pos - src;
- a->block_offset &= (AES_BLOCK_SIZE - 1);
+ while (count >= AES_BLOCK_SIZE) {
+ av_aes_crypt(&a->aes, a->encrypted_counter, a->counter, 1, NULL, 0);
+ av_aes_ctr_increment_be64(a->counter + 8);
+#if HAVE_FAST_64BIT
+ for (int len = 0; len < AES_BLOCK_SIZE; len += 8)
+ AV_WN64(&dst[len], AV_RN64(&src[len]) ^
AV_RN64A(&a->encrypted_counter[len]));
+#else
+ for (int len = 0; len < AES_BLOCK_SIZE; len += 4)
+ AV_WN32(&dst[len], AV_RN32(&src[len]) ^
AV_RN32A(&a->encrypted_counter[len]));
+#endif
+ dst += AES_BLOCK_SIZE;
+ src += AES_BLOCK_SIZE;
+ count -= AES_BLOCK_SIZE;
+ }
- while (src < cur_end_pos) {
- *dst++ = *src++ ^ *encrypted_counter_pos++;
- }
+ if (count > 0) {
+ av_aes_crypt(&a->aes, a->encrypted_counter, a->counter, 1, NULL, 0);
+ av_aes_ctr_increment_be64(a->counter + 8);
+ for (int len = 0; len < count; len++)
+ dst[len] = src[len] ^ a->encrypted_counter[len];
}
}
--
2.49.0
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