diff options
Diffstat (limited to 'pixman/pixman/pixman-mmx.c')
| -rw-r--r-- | pixman/pixman/pixman-mmx.c | 82 |
1 files changed, 38 insertions, 44 deletions
diff --git a/pixman/pixman/pixman-mmx.c b/pixman/pixman/pixman-mmx.c index 39e85c586..ed5107321 100644 --- a/pixman/pixman/pixman-mmx.c +++ b/pixman/pixman/pixman-mmx.c @@ -309,6 +309,29 @@ negate (__m64 mask) return _mm_xor_si64 (mask, MC (4x00ff)); } +/* Computes the product of two unsigned fixed-point 8-bit values from 0 to 1 + * and maps its result to the same range. + * + * Jim Blinn gives multiple ways to compute this in "Jim Blinn's Corner: + * Notation, Notation, Notation", the first of which is + * + * prod(a, b) = (a * b + 128) / 255. + * + * By approximating the division by 255 as 257/65536 it can be replaced by a + * multiply and a right shift. This is the implementation that we use in + * pix_multiply(), but we _mm_mulhi_pu16() by 257 (part of SSE1 or Extended + * 3DNow!, and unavailable at the time of the book's publication) to perform + * the multiplication and right shift in a single operation. + * + * prod(a, b) = ((a * b + 128) * 257) >> 16. + * + * A third way (how pix_multiply() was implemented prior to 14208344) exists + * also that performs the multiplication by 257 with adds and shifts. + * + * Where temp = a * b + 128 + * + * prod(a, b) = (temp + (temp >> 8)) >> 8. + */ static force_inline __m64 pix_multiply (__m64 a, __m64 b) { @@ -3926,52 +3949,23 @@ mmx_fetch_a8 (pixman_iter_t *iter, const uint32_t *mask) return iter->buffer; } -typedef struct -{ - pixman_format_code_t format; - pixman_iter_get_scanline_t get_scanline; -} fetcher_info_t; - -static const fetcher_info_t fetchers[] = -{ - { PIXMAN_x8r8g8b8, mmx_fetch_x8r8g8b8 }, - { PIXMAN_r5g6b5, mmx_fetch_r5g6b5 }, - { PIXMAN_a8, mmx_fetch_a8 }, - { PIXMAN_null } -}; - -static pixman_bool_t -mmx_src_iter_init (pixman_implementation_t *imp, pixman_iter_t *iter) -{ - pixman_image_t *image = iter->image; - -#define FLAGS \ +#define IMAGE_FLAGS \ (FAST_PATH_STANDARD_FLAGS | FAST_PATH_ID_TRANSFORM | \ FAST_PATH_BITS_IMAGE | FAST_PATH_SAMPLES_COVER_CLIP_NEAREST) - if ((iter->iter_flags & ITER_NARROW) && - (iter->image_flags & FLAGS) == FLAGS) - { - const fetcher_info_t *f; - - for (f = &fetchers[0]; f->format != PIXMAN_null; f++) - { - if (image->common.extended_format_code == f->format) - { - uint8_t *b = (uint8_t *)image->bits.bits; - int s = image->bits.rowstride * 4; - - iter->bits = b + s * iter->y + iter->x * PIXMAN_FORMAT_BPP (f->format) / 8; - iter->stride = s; - - iter->get_scanline = f->get_scanline; - return TRUE; - } - } - } - - return FALSE; -} +static const pixman_iter_info_t mmx_iters[] = +{ + { PIXMAN_x8r8g8b8, IMAGE_FLAGS, ITER_NARROW, + _pixman_iter_init_bits_stride, mmx_fetch_x8r8g8b8, NULL + }, + { PIXMAN_r5g6b5, IMAGE_FLAGS, ITER_NARROW, + _pixman_iter_init_bits_stride, mmx_fetch_r5g6b5, NULL + }, + { PIXMAN_a8, IMAGE_FLAGS, ITER_NARROW, + _pixman_iter_init_bits_stride, mmx_fetch_a8, NULL + }, + { PIXMAN_null }, +}; static const pixman_fast_path_t mmx_fast_paths[] = { @@ -4101,7 +4095,7 @@ _pixman_implementation_create_mmx (pixman_implementation_t *fallback) imp->blt = mmx_blt; imp->fill = mmx_fill; - imp->src_iter_init = mmx_src_iter_init; + imp->iter_info = mmx_iters; return imp; } |