On Thu, 22 Jan 2015 01:38:11 +0530
arwa arif <arwaarif1...@gmail.com> wrote:
> From 703cc1887903c2868537e19e99b76927bec07884 Mon Sep 17 00:00:00 2001
> From: Arwa Arif <arwaarif1...@gmail.com>
> Date: Mon, 19 Jan 2015 03:56:48 +0530
> Subject: [PATCH] Port mp=eq/eq2 to FFmpeg
>
> Code adapted from James Darnley's previous commits
> [...]
> +#if HAVE_MMX && HAVE_6REGS
> +static void process_MMX(EQParameters *param, uint8_t *dst, int dst_stride,
> + uint8_t *src, int src_stride, int w, int h)
> +{
> + int i;
> + int pel;
> + int dstep = dst_stride - w;
> + int sstep = src_stride - w;
> + short brvec[4];
> + short contvec[4];
> +
> + brvec[0] = brvec[1] = brvec[2] = brvec[3] = param->b;
> + contvec[0] = contvec[1] = contvec[2] = contvec[3] = param->c;
> +
> + while (h--) {
> + __asm__ volatile (
> + "movq (%5), %%mm3 \n\t"
> + "movq (%6), %%mm4 \n\t"
> + "pxor %%mm0, %%mm0 \n\t"
> + "movl %4, %%eax \n\t"
> + //ASMALIGN(4)
> + "1: \n\t"
> + "movq (%0), %%mm1 \n\t"
> + "movq (%0), %%mm2 \n\t"
> + "punpcklbw %%mm0, %%mm1\n\t"
> + "punpckhbw %%mm0, %%mm2\n\t"
> + "psllw $4, %%mm1 \n\t"
> + "psllw $4, %%mm2 \n\t"
> + "pmulhw %%mm4, %%mm1 \n\t"
> + "pmulhw %%mm4, %%mm2 \n\t"
> + "paddw %%mm3, %%mm1 \n\t"
> + "paddw %%mm3, %%mm2 \n\t"
> + "packuswb %%mm2, %%mm1 \n\t"
> + "add $8, %0 \n\t"
> + "movq %%mm1, (%1) \n\t"
> + "add $8, %1 \n\t"
> + "decl %%eax \n\t"
> + "jnz 1b \n\t"
> + : "=r" (src), "=r" (dst)
> + : "0" (src), "1" (dst), "r" (w>>3), "r" (brvec), "r"
> (contvec)
> + : "%eax"
> + );
> +
> + for (i = w&7; i; i--) {
> + pel = ((*src++ * param->c) >> 12) + param->b;
> + if (pel & 768)
> + pel = (-pel) >> 31;
> + *dst++ = pel;
> + }
> +
> + src += sstep;
> + dst += dstep;
> + }
> + __asm__ volatile ( "emms \n\t" ::: "memory" );
> +}
> +#endif
IMO the asm shouldn't be added at all. It's not important enough for a
ported video filter, but has high maintenance overhead - there's a
reason the FFmpeg loathes inline asm, right?
How much does the inline asm help with speed? When I tested it on a
reasonably modern CPU a while ago, there was barely any advantage.
> +av_cold void ff_eq_init_x86(EQContext *eq)
> +{
> +#if HAVE_MMX_INLINE
> + int cpu_flags = av_get_cpu_flags();
> +
> + if (cpu_flags & AV_CPU_FLAG_MMX) {
> + eq->process = process_MMX;
> + }
> +#endif
> +}
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