[vlc-commits] aes3: use lookup table to speed up bit order inversion
Rémi Denis-Courmont
git at videolan.org
Tue Nov 20 21:46:11 CET 2012
vlc | branch: master | Rémi Denis-Courmont <remi at remlab.net> | Tue Nov 20 21:27:11 2012 +0200| [db8b580100f1e6c0e8f40269b0af1b08595ce011] | committer: Rémi Denis-Courmont
aes3: use lookup table to speed up bit order inversion
> http://git.videolan.org/gitweb.cgi/vlc.git/?a=commit;h=db8b580100f1e6c0e8f40269b0af1b08595ce011
---
modules/codec/aes3.c | 76 +++++++++++++++++++++++++++++++++-----------------
1 file changed, 51 insertions(+), 25 deletions(-)
diff --git a/modules/codec/aes3.c b/modules/codec/aes3.c
index bad1af6..ea9ceae 100644
--- a/modules/codec/aes3.c
+++ b/modules/codec/aes3.c
@@ -76,14 +76,6 @@ static int Open( decoder_t *p_dec, bool b_packetizer );
static block_t *Parse( decoder_t *p_dec, int *pi_frame_length, int *pi_bits,
block_t **pp_block, bool b_packetizer );
-static inline uint8_t Reverse8( int n )
-{
- n = ((n >> 1) & 0x55) | ((n << 1) & 0xaa);
- n = ((n >> 2) & 0x33) | ((n << 2) & 0xcc);
- n = ((n >> 4) & 0x0f) | ((n << 4) & 0xf0);
- return n;
-}
-
/*****************************************************************************
* OpenDecoder:
*****************************************************************************/
@@ -113,6 +105,31 @@ static void Close( vlc_object_t *p_this )
free( p_dec->p_sys );
}
+static const uint8_t reverse[256] = {
+ 0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, 0x60, 0xe0, 0x10, 0x90, 0x50, 0xd0,
+ 0x30, 0xb0, 0x70, 0xf0, 0x08, 0x88, 0x48, 0xc8, 0x28, 0xa8, 0x68, 0xe8,
+ 0x18, 0x98, 0x58, 0xd8, 0x38, 0xb8, 0x78, 0xf8, 0x04, 0x84, 0x44, 0xc4,
+ 0x24, 0xa4, 0x64, 0xe4, 0x14, 0x94, 0x54, 0xd4, 0x34, 0xb4, 0x74, 0xf4,
+ 0x0c, 0x8c, 0x4c, 0xcc, 0x2c, 0xac, 0x6c, 0xec, 0x1c, 0x9c, 0x5c, 0xdc,
+ 0x3c, 0xbc, 0x7c, 0xfc, 0x02, 0x82, 0x42, 0xc2, 0x22, 0xa2, 0x62, 0xe2,
+ 0x12, 0x92, 0x52, 0xd2, 0x32, 0xb2, 0x72, 0xf2, 0x0a, 0x8a, 0x4a, 0xca,
+ 0x2a, 0xaa, 0x6a, 0xea, 0x1a, 0x9a, 0x5a, 0xda, 0x3a, 0xba, 0x7a, 0xfa,
+ 0x06, 0x86, 0x46, 0xc6, 0x26, 0xa6, 0x66, 0xe6, 0x16, 0x96, 0x56, 0xd6,
+ 0x36, 0xb6, 0x76, 0xf6, 0x0e, 0x8e, 0x4e, 0xce, 0x2e, 0xae, 0x6e, 0xee,
+ 0x1e, 0x9e, 0x5e, 0xde, 0x3e, 0xbe, 0x7e, 0xfe, 0x01, 0x81, 0x41, 0xc1,
+ 0x21, 0xa1, 0x61, 0xe1, 0x11, 0x91, 0x51, 0xd1, 0x31, 0xb1, 0x71, 0xf1,
+ 0x09, 0x89, 0x49, 0xc9, 0x29, 0xa9, 0x69, 0xe9, 0x19, 0x99, 0x59, 0xd9,
+ 0x39, 0xb9, 0x79, 0xf9, 0x05, 0x85, 0x45, 0xc5, 0x25, 0xa5, 0x65, 0xe5,
+ 0x15, 0x95, 0x55, 0xd5, 0x35, 0xb5, 0x75, 0xf5, 0x0d, 0x8d, 0x4d, 0xcd,
+ 0x2d, 0xad, 0x6d, 0xed, 0x1d, 0x9d, 0x5d, 0xdd, 0x3d, 0xbd, 0x7d, 0xfd,
+ 0x03, 0x83, 0x43, 0xc3, 0x23, 0xa3, 0x63, 0xe3, 0x13, 0x93, 0x53, 0xd3,
+ 0x33, 0xb3, 0x73, 0xf3, 0x0b, 0x8b, 0x4b, 0xcb, 0x2b, 0xab, 0x6b, 0xeb,
+ 0x1b, 0x9b, 0x5b, 0xdb, 0x3b, 0xbb, 0x7b, 0xfb, 0x07, 0x87, 0x47, 0xc7,
+ 0x27, 0xa7, 0x67, 0xe7, 0x17, 0x97, 0x57, 0xd7, 0x37, 0xb7, 0x77, 0xf7,
+ 0x0f, 0x8f, 0x4f, 0xcf, 0x2f, 0xaf, 0x6f, 0xef, 0x1f, 0x9f, 0x5f, 0xdf,
+ 0x3f, 0xbf, 0x7f, 0xff
+};
+
/*****************************************************************************
* Decode: decodes an aes3 frame.
****************************************************************************
@@ -146,13 +163,16 @@ static block_t *Decode( decoder_t *p_dec, block_t **pp_block )
while( p_block->i_buffer / 7 )
{
- p_out[0] = Reverse8( p_block->p_buffer[0] );
- p_out[1] = Reverse8( p_block->p_buffer[1] );
- p_out[2] = Reverse8( p_block->p_buffer[2] );
+ p_out[0] = reverse[p_block->p_buffer[0]];
+ p_out[1] = reverse[p_block->p_buffer[1]];
+ p_out[2] = reverse[p_block->p_buffer[2]];
- p_out[3] = (Reverse8( p_block->p_buffer[3] ) >> 4) | ( (Reverse8( p_block->p_buffer[4] ) << 4) & 0xf0 );
- p_out[4] = (Reverse8( p_block->p_buffer[4] ) >> 4) | ( (Reverse8( p_block->p_buffer[5] ) << 4) & 0xf0 );
- p_out[5] = (Reverse8( p_block->p_buffer[5] ) >> 4) | ( (Reverse8( p_block->p_buffer[6] ) << 4) & 0xf0 );
+ p_out[3] = (reverse[p_block->p_buffer[3]] >> 4)
+ | ((reverse[p_block->p_buffer[4]] << 4) & 0xf0);
+ p_out[4] = (reverse[p_block->p_buffer[4]] >> 4)
+ | ((reverse[p_block->p_buffer[5]] << 4) & 0xf0);
+ p_out[5] = (reverse[p_block->p_buffer[5]] >> 4)
+ | ((reverse[p_block->p_buffer[6]] << 4) & 0xf0);
p_block->i_buffer -= 7;
p_block->p_buffer += 7;
@@ -166,13 +186,17 @@ static block_t *Decode( decoder_t *p_dec, block_t **pp_block )
while( p_block->i_buffer / 6 )
{
- p_out[0] = ( (Reverse8( p_block->p_buffer[0] ) << 4) & 0xf0 );
- p_out[1] = ( Reverse8( p_block->p_buffer[0]) >> 4 ) | ( (Reverse8( p_block->p_buffer[1]) << 4 ) & 0xf0 );
- p_out[2] = ( Reverse8( p_block->p_buffer[1]) >> 4 ) | ( (Reverse8( p_block->p_buffer[2]) << 4 ) & 0xf0 );
-
- p_out[3] = ( (Reverse8( p_block->p_buffer[3] ) << 4) & 0xf0 );
- p_out[4] = ( Reverse8( p_block->p_buffer[3]) >> 4 ) | ( (Reverse8( p_block->p_buffer[4]) << 4 ) & 0xf0 );
- p_out[5] = ( Reverse8( p_block->p_buffer[4]) >> 4 ) | ( (Reverse8( p_block->p_buffer[5]) << 4 ) & 0xf0 );
+ p_out[0] = ((reverse[p_block->p_buffer[0]] << 4) & 0xf0);
+ p_out[1] = (reverse[p_block->p_buffer[0]] >> 4)
+ | ((reverse[p_block->p_buffer[1]] << 4) & 0xf0);
+ p_out[2] = (reverse[p_block->p_buffer[1]] >> 4)
+ | ((reverse[p_block->p_buffer[2]] << 4) & 0xf0);
+
+ p_out[3] = ((reverse[p_block->p_buffer[3]] << 4) & 0xf0);
+ p_out[4] = (reverse[p_block->p_buffer[3]] >> 4)
+ | ((reverse[p_block->p_buffer[4]] << 4) & 0xf0);
+ p_out[5] = (reverse[p_block->p_buffer[4]] >> 4)
+ | ((reverse[p_block->p_buffer[5]] << 4) & 0xf0);
p_block->i_buffer -= 6;
p_block->p_buffer += 6;
@@ -187,11 +211,13 @@ static block_t *Decode( decoder_t *p_dec, block_t **pp_block )
while( p_block->i_buffer / 5 )
{
- p_out[0] = Reverse8( p_block->p_buffer[0] );
- p_out[1] = Reverse8( p_block->p_buffer[1] );
+ p_out[0] = reverse[p_block->p_buffer[0]];
+ p_out[1] = reverse[p_block->p_buffer[1]];
- p_out[2] = (Reverse8( p_block->p_buffer[2] ) >> 4) | ( (Reverse8( p_block->p_buffer[3] ) << 4) & 0xf0 );
- p_out[3] = (Reverse8( p_block->p_buffer[3] ) >> 4) | ( (Reverse8( p_block->p_buffer[4] ) << 4) & 0xf0 );
+ p_out[2] = (reverse[p_block->p_buffer[2]] >> 4)
+ | ((reverse[p_block->p_buffer[3]] << 4) & 0xf0);
+ p_out[3] = (reverse[p_block->p_buffer[3]] >> 4)
+ | ((reverse[p_block->p_buffer[4]] << 4) & 0xf0);
p_block->i_buffer -= 5;
p_block->p_buffer += 5;
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