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With a dereferenced type-cast pointer as memory operand, gcc 4.6 and later will sometimes copy the data to a temporary location, the address of which is used as the operand value, if it thinks the target address might be misaligned. Using a pointer to a packed struct type instead does the right thing. The 16-bit case is special since the ldrh instruction addressing modes are limited compared to ldr. The "Uq" constraint produces a memory reference suitable for an ldrsb instruction, which supports the same addressing modes as ldrh. However, the restrictions appear to apply only when the operand addresses a single byte. The memory reference must thus be split into two operands each targeting one byte. Finally, the "Uq" constraint is only available in ARM mode. The Thumb-2 ldrh instruction supports most addressing modes so the normal "m" constraint can be used there. Signed-off-by: Mans Rullgard <mans@mansr.com> |
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| doc | ||
| libavcodec | ||
| libavdevice | ||
| libavfilter | ||
| libavformat | ||
| libavresample | ||
| libavutil | ||
| libswscale | ||
| presets | ||
| tests | ||
| tools | ||
| .gitignore | ||
| arch.mak | ||
| avconv.c | ||
| avplay.c | ||
| avprobe.c | ||
| avserver.c | ||
| Changelog | ||
| cmdutils_common_opts.h | ||
| cmdutils.c | ||
| cmdutils.h | ||
| common.mak | ||
| configure | ||
| COPYING.GPLv2 | ||
| COPYING.GPLv3 | ||
| COPYING.LGPLv2.1 | ||
| COPYING.LGPLv3 | ||
| CREDITS | ||
| Doxyfile | ||
| INSTALL | ||
| library.mak | ||
| LICENSE | ||
| Makefile | ||
| README | ||
| RELEASE | ||
| version.sh | ||
Libav README ------------ 1) Documentation ---------------- * Read the documentation in the doc/ directory. 2) Licensing ------------ * See the LICENSE file.