FFmpeg

29935 Commits

37 Branches

400 Tags

479 MiB

Tag: Branch: Tree: 445ee35e21

Commit Graph

Author	SHA1	Message	Date
Aurelien Jacobs	13d4ec844a	cosmetics: alignment	14 years ago
pin xue	05c062e9da	replace movw instruction in ac3dsp_armv6.S AS libavcodec/arm/ac3dsp_armv6.o ffmpeg-src/libavcodec/arm/ac3dsp_armv6.S: Assembler messages: ffmpeg-src/libavcodec/arm/ac3dsp_armv6.S:40: Error: selected processor does not support `movw r8,#0x1fe0' make[1]: *** [libavcodec/arm/ac3dsp_armv6.o] Error 1 MOVW is ARMv7 way to load constant: * movw, or move wide, will move a 16-bit constant into a register, implicitly zeroing the top 16 bits of the target register. * movt, or move top, will move a 16-bit constant into the top half of a given register without altering the bottom 16 bits To load 32 bit constant, movw lower16; movt upper16; is better than ldr if available, because: While this approach takes two instructions, it does not require any extra space to store the constant so both the movw/movt method and the ldr method will end up using the same amount of memory. Memory bandwidth is precious in and the movw/movt approach avoids an extra read on the data side, not to mention the read could have missed the cache. But here it is armv6 optimization, so that we have to use ldr. Signed-off-by: Michael Niedermayer <michaelni@gmx.at>	14 years ago
Mans Rullgard	182826c884	ac3: armv6 optimised bit_alloc_calc_bap Signed-off-by: Mans Rullgard <mans@mansr.com>	14 years ago

Author

SHA1

Message

Date

Aurelien Jacobs

13d4ec844a

cosmetics: alignment

14 years ago

pin xue

05c062e9da

replace movw instruction in ac3dsp_armv6.S

AS      libavcodec/arm/ac3dsp_armv6.o
ffmpeg-src/libavcodec/arm/ac3dsp_armv6.S: Assembler messages:
ffmpeg-src/libavcodec/arm/ac3dsp_armv6.S:40: Error: selected processor
does not support `movw r8,#0x1fe0'
make[1]: *** [libavcodec/arm/ac3dsp_armv6.o] Error 1

MOVW is ARMv7 way to load constant:
   * movw, or move wide, will move a 16-bit constant into a register,
implicitly zeroing the top 16 bits of the target register.
   * movt, or move top, will move a 16-bit constant into the top half
of a given register without altering the bottom 16 bits
To load 32 bit constant, movw  lower16; movt upper16; is better than
ldr if available, because:
While this approach takes two instructions, it does not require any
extra space to store the constant so both the movw/movt method and the
ldr method will end up using the same amount of memory. Memory
bandwidth is precious in and the movw/movt approach avoids an extra
read on the data side, not to mention the read could have missed the
cache.

But here it is armv6 optimization, so that we have to use ldr.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

14 years ago

Mans Rullgard

182826c884

ac3: armv6 optimised bit_alloc_calc_bap

Signed-off-by: Mans Rullgard <mans@mansr.com>

14 years ago

3 Commits (445ee35e21c92e2429241d65bdba65f6e7c09132)