[x264-devel] Re: [PATCH] Altivec optimizations for quant4x4, quant4x4dc, quant8x8, sub8x8_dct8, sub16x16_dct8, pixel_sa8d_8x8, pixel_sa8d_16x16, *idct8*

[David Wolstencroft]

Sooo, ok, since I'm wired (don't know why I can't sleep....)


if (dst is 16 byte aligned)
	
#define ALTIVEC_STORE_SUM_CLIP_ALIGN8_A(dest, idctv) {\
     vec_u8_t dstv = vec_ld(0, dest);\
     vec_s16_t idct_sh6 = vec_sra(idctv, sixv);\
     vec_u16_t dst16h = vec_mergeh(zero_u8v, dstv);\
     vec_u16_t dst16l = vec_mergel(zero_u8v, dstv);\
     vec_s16_t sum16 = vec_adds(idct_sh6, (vec_s16_t)dst16h);\
     vec_u8_t sum8 = vec_packsu(sum16, dst16l);\       <- I swear  
pengvado made a mistake here, if that's possible
     vec_st(sum8, 0, dest);\

else (8 byte aligned but not 16 byte aligned)

#define ALTIVEC_STORE_SUM_CLIP_ALIGN8_A(dest, idctv) {\
     vec_u8_t dstv = vec_ld(0, dest);\
     vec_s16_t idct_sh6 = vec_sra(idctv, sixv);\
     vec_u16_t dst16h = vec_mergeh(zero_u8v, dstv);\
     vec_u16_t dst16l = vec_mergel(zero_u8v, dstv);\
     vec_s16_t sum16 = vec_adds(idct_sh6, (vec_s16_t)dst16);\
     vec_u8_t sum8 = vec_packsu(dst16h, sum16);\
     vec_st(sum8, 0, dest);\



On Sep 18, 2006, at 12:24 PM, Loren Merritt wrote:

> #define ALTIVEC_STORE_SUM_CLIP_ALIGN8_A(dest, idctv) {\
>     vec_u8_t dstv = vec_ld(0, dest);\
>     vec_s16_t idct_sh6 = vec_sra(idctv, sixv);\
>     vec_u16_t dst16h = vec_mergeh(zero_u8v, dstv);\
>     vec_u16_t dst16l = vec_mergel(zero_u8v, dstv);\
>     vec_s16_t sum16 = vec_adds(idct_sh6, (vec_s16_t)dst16h);\
>     vec_u8_t sum8 = vec_packsu(dst16l, sum16);\
>     vec_st(sum8, 0, dest);\

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