GNU as evaluates true as '-1' while Apple's variant and llvm's internal
assembler evaluate it as '1'. The best way to avoid this madness is to
eliminate boolean expressions instead of trying to fix it with
preprocessor directives. Use a direct formula to calculate the
required temporary space on the stack in
ff_put_vp8_{epel,bilin}{4,8,16}_h[246]v[246]_armv6().

Fixes a checkasm segfault in vp8dsp.mc when using llvm's internal
assembler for a non-Apple target.

Signed-off-by: Martin Storsjö <martin@martin.st>

The integrated arm assembler in clang-503.0.38 (Xcode-5.1) fails
to assemble a branch to 'label + offset' in thumb mode.

Don't rely on the fact that an unprefixed label currently exists.
Signed-off-by: Martin Storsjö <martin@martin.st>

This makes the plain-armv6 version use the same registers as the
armv6t2 version above.

This fixes fate-vp8 on plain-armv6 devices.
Signed-off-by: Martin Storsjö <martin@martin.st>

It does not help as an abstraction and adds dsputil dependencies.
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>

These macros reflect the actual capabilities required here.
Signed-off-by: Mans Rullgard <mans@mansr.com>

In the GNU assembler, a relational expression, bizarrely, has the
value -1 if true, whereas in Apple's it is +1.  This patch makes
sure the correct expression is used in both cases.
Signed-off-by: Mans Rullgard <mans@mansr.com>

This will allow for easier implementation of ARM-optimized functions in
libraries other than libavcodec.

The assembler may fail to place literal pools close enough to
instructions referencing them.  An explicit .ltorg directive
fixes this.
Signed-off-by: Mans Rullgard <mans@mansr.com>

Based on patch by Ronald S. Bultje <rsbultje@gmail.com>,
partially ported from libvpx.
Signed-off-by: Mans Rullgard <mans@mansr.com>

This is a preparation for complete ARMv6 optimisations.
Signed-off-by: Mans Rullgard <mans@mansr.com>