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1 /*
2  * AltiVec optimizations for libjpeg-turbo
3  *
4  * Copyright (C) 2014-2015, D. R. Commander.  All Rights Reserved.
5  * Copyright (C) 2014, Jay Foad.  All Rights Reserved.
6  *
7  * This software is provided 'as-is', without any express or implied
8  * warranty.  In no event will the authors be held liable for any damages
9  * arising from the use of this software.
10  *
11  * Permission is granted to anyone to use this software for any purpose,
12  * including commercial applications, and to alter it and redistribute it
13  * freely, subject to the following restrictions:
14  *
15  * 1. The origin of this software must not be misrepresented; you must not
16  *    claim that you wrote the original software. If you use this software
17  *    in a product, an acknowledgment in the product documentation would be
18  *    appreciated but is not required.
19  * 2. Altered source versions must be plainly marked as such, and must not be
20  *    misrepresented as being the original software.
21  * 3. This notice may not be removed or altered from any source distribution.
22  */
23 
24 /* This file is included by jccolor-altivec.c */
25 
26 
jsimd_rgb_ycc_convert_altivec(JDIMENSION img_width,JSAMPARRAY input_buf,JSAMPIMAGE output_buf,JDIMENSION output_row,int num_rows)27 void jsimd_rgb_ycc_convert_altivec(JDIMENSION img_width, JSAMPARRAY input_buf,
28                                    JSAMPIMAGE output_buf,
29                                    JDIMENSION output_row, int num_rows)
30 {
31   JSAMPROW inptr, outptr0, outptr1, outptr2;
32   int pitch = img_width * RGB_PIXELSIZE, num_cols;
33 #if __BIG_ENDIAN__
34   int offset;
35 #endif
36   unsigned char __attribute__((aligned(16))) tmpbuf[RGB_PIXELSIZE * 16];
37 
38   __vector unsigned char rgb0, rgb1 = { 0 }, rgb2 = { 0 },
39     rgbg0, rgbg1, rgbg2, rgbg3, y, cb, cr;
40 #if __BIG_ENDIAN__ || RGB_PIXELSIZE == 4
41   __vector unsigned char rgb3 = { 0 };
42 #endif
43 #if __BIG_ENDIAN__ && RGB_PIXELSIZE == 4
44   __vector unsigned char rgb4 = { 0 };
45 #endif
46   __vector short rg0, rg1, rg2, rg3, bg0, bg1, bg2, bg3;
47   __vector unsigned short yl, yh, crl, crh, cbl, cbh;
48   __vector int y0, y1, y2, y3, cr0, cr1, cr2, cr3, cb0, cb1, cb2, cb3;
49 
50   /* Constants */
51   __vector short pw_f0299_f0337 = { __4X2(F_0_299, F_0_337) },
52     pw_f0114_f0250 = { __4X2(F_0_114, F_0_250) },
53     pw_mf016_mf033 = { __4X2(-F_0_168, -F_0_331) },
54     pw_mf008_mf041 = { __4X2(-F_0_081, -F_0_418) };
55   __vector unsigned short pw_f050_f000 = { __4X2(F_0_500, 0) };
56   __vector int pd_onehalf = { __4X(ONE_HALF) },
57     pd_onehalfm1_cj = { __4X(ONE_HALF - 1 + (CENTERJSAMPLE << SCALEBITS)) };
58   __vector unsigned char pb_zero = { __16X(0) },
59 #if __BIG_ENDIAN__
60     shift_pack_index =
61       {  0,  1,  4,  5,  8,  9, 12, 13, 16, 17, 20, 21, 24, 25, 28, 29 };
62 #else
63     shift_pack_index =
64       {  2,  3,  6,  7, 10, 11, 14, 15, 18, 19, 22, 23, 26, 27, 30, 31 };
65 #endif
66 
67   while (--num_rows >= 0) {
68     inptr = *input_buf++;
69     outptr0 = output_buf[0][output_row];
70     outptr1 = output_buf[1][output_row];
71     outptr2 = output_buf[2][output_row];
72     output_row++;
73 
74     for (num_cols = pitch; num_cols > 0;
75          num_cols -= RGB_PIXELSIZE * 16, inptr += RGB_PIXELSIZE * 16,
76          outptr0 += 16, outptr1 += 16, outptr2 += 16) {
77 
78 #if __BIG_ENDIAN__
79       /* Load 16 pixels == 48 or 64 bytes */
80       offset = (size_t)inptr & 15;
81       if (offset) {
82         __vector unsigned char unaligned_shift_index;
83         int bytes = num_cols + offset;
84 
85         if (bytes < (RGB_PIXELSIZE + 1) * 16 && (bytes & 15)) {
86           /* Slow path to prevent buffer overread.  Since there is no way to
87            * read a partial AltiVec register, overread would occur on the last
88            * chunk of the last image row if the right edge is not on a 16-byte
89            * boundary.  It could also occur on other rows if the bytes per row
90            * is low enough.  Since we can't determine whether we're on the last
91            * image row, we have to assume every row is the last.
92            */
93           memcpy(tmpbuf, inptr, min(num_cols, RGB_PIXELSIZE * 16));
94           rgb0 = vec_ld(0, tmpbuf);
95           rgb1 = vec_ld(16, tmpbuf);
96           rgb2 = vec_ld(32, tmpbuf);
97 #if RGB_PIXELSIZE == 4
98           rgb3 = vec_ld(48, tmpbuf);
99 #endif
100         } else {
101           /* Fast path */
102           rgb0 = vec_ld(0, inptr);
103           if (bytes > 16)
104             rgb1 = vec_ld(16, inptr);
105           if (bytes > 32)
106             rgb2 = vec_ld(32, inptr);
107           if (bytes > 48)
108             rgb3 = vec_ld(48, inptr);
109 #if RGB_PIXELSIZE == 4
110           if (bytes > 64)
111             rgb4 = vec_ld(64, inptr);
112 #endif
113           unaligned_shift_index = vec_lvsl(0, inptr);
114           rgb0 = vec_perm(rgb0, rgb1, unaligned_shift_index);
115           rgb1 = vec_perm(rgb1, rgb2, unaligned_shift_index);
116           rgb2 = vec_perm(rgb2, rgb3, unaligned_shift_index);
117 #if RGB_PIXELSIZE == 4
118           rgb3 = vec_perm(rgb3, rgb4, unaligned_shift_index);
119 #endif
120         }
121       } else {
122 #endif /* __BIG_ENDIAN__ */
123         if (num_cols < RGB_PIXELSIZE * 16 && (num_cols & 15)) {
124           /* Slow path */
125           memcpy(tmpbuf, inptr, min(num_cols, RGB_PIXELSIZE * 16));
126           rgb0 = VEC_LD(0, tmpbuf);
127           rgb1 = VEC_LD(16, tmpbuf);
128           rgb2 = VEC_LD(32, tmpbuf);
129 #if RGB_PIXELSIZE == 4
130           rgb3 = VEC_LD(48, tmpbuf);
131 #endif
132         } else {
133           /* Fast path */
134           rgb0 = VEC_LD(0, inptr);
135           if (num_cols > 16)
136             rgb1 = VEC_LD(16, inptr);
137           if (num_cols > 32)
138             rgb2 = VEC_LD(32, inptr);
139 #if RGB_PIXELSIZE == 4
140           if (num_cols > 48)
141             rgb3 = VEC_LD(48, inptr);
142 #endif
143         }
144 #if __BIG_ENDIAN__
145       }
146 #endif
147 
148 #if RGB_PIXELSIZE == 3
149       /* rgb0 = R0 G0 B0 R1 G1 B1 R2 G2 B2 R3 G3 B3 R4 G4 B4 R5
150        * rgb1 = G5 B5 R6 G6 B6 R7 G7 B7 R8 G8 B8 R9 G9 B9 Ra Ga
151        * rgb2 = Ba Rb Gb Bb Rc Gc Bc Rd Gd Bd Re Ge Be Rf Gf Bf
152        *
153        * rgbg0 = R0 G0 R1 G1 R2 G2 R3 G3 B0 G0 B1 G1 B2 G2 B3 G3
154        * rgbg1 = R4 G4 R5 G5 R6 G6 R7 G7 B4 G4 B5 G5 B6 G6 B7 G7
155        * rgbg2 = R8 G8 R9 G9 Ra Ga Rb Gb B8 G8 B9 G9 Ba Ga Bb Gb
156        * rgbg3 = Rc Gc Rd Gd Re Ge Rf Gf Bc Gc Bd Gd Be Ge Bf Gf
157        */
158       rgbg0 = vec_perm(rgb0, rgb0, (__vector unsigned char)RGBG_INDEX0);
159       rgbg1 = vec_perm(rgb0, rgb1, (__vector unsigned char)RGBG_INDEX1);
160       rgbg2 = vec_perm(rgb1, rgb2, (__vector unsigned char)RGBG_INDEX2);
161       rgbg3 = vec_perm(rgb2, rgb2, (__vector unsigned char)RGBG_INDEX3);
162 #else
163       /* rgb0 = R0 G0 B0 X0 R1 G1 B1 X1 R2 G2 B2 X2 R3 G3 B3 X3
164        * rgb1 = R4 G4 B4 X4 R5 G5 B5 X5 R6 G6 B6 X6 R7 G7 B7 X7
165        * rgb2 = R8 G8 B8 X8 R9 G9 B9 X9 Ra Ga Ba Xa Rb Gb Bb Xb
166        * rgb3 = Rc Gc Bc Xc Rd Gd Bd Xd Re Ge Be Xe Rf Gf Bf Xf
167        *
168        * rgbg0 = R0 G0 R1 G1 R2 G2 R3 G3 B0 G0 B1 G1 B2 G2 B3 G3
169        * rgbg1 = R4 G4 R5 G5 R6 G6 R7 G7 B4 G4 B5 G5 B6 G6 B7 G7
170        * rgbg2 = R8 G8 R9 G9 Ra Ga Rb Gb B8 G8 B9 G9 Ba Ga Bb Gb
171        * rgbg3 = Rc Gc Rd Gd Re Ge Rf Gf Bc Gc Bd Gd Be Ge Bf Gf
172        */
173       rgbg0 = vec_perm(rgb0, rgb0, (__vector unsigned char)RGBG_INDEX);
174       rgbg1 = vec_perm(rgb1, rgb1, (__vector unsigned char)RGBG_INDEX);
175       rgbg2 = vec_perm(rgb2, rgb2, (__vector unsigned char)RGBG_INDEX);
176       rgbg3 = vec_perm(rgb3, rgb3, (__vector unsigned char)RGBG_INDEX);
177 #endif
178 
179       /* rg0 = R0 G0 R1 G1 R2 G2 R3 G3
180        * bg0 = B0 G0 B1 G1 B2 G2 B3 G3
181        * ...
182        *
183        * NOTE: We have to use vec_merge*() here because vec_unpack*() doesn't
184        * support unsigned vectors.
185        */
186       rg0 = (__vector signed short)VEC_UNPACKHU(rgbg0);
187       bg0 = (__vector signed short)VEC_UNPACKLU(rgbg0);
188       rg1 = (__vector signed short)VEC_UNPACKHU(rgbg1);
189       bg1 = (__vector signed short)VEC_UNPACKLU(rgbg1);
190       rg2 = (__vector signed short)VEC_UNPACKHU(rgbg2);
191       bg2 = (__vector signed short)VEC_UNPACKLU(rgbg2);
192       rg3 = (__vector signed short)VEC_UNPACKHU(rgbg3);
193       bg3 = (__vector signed short)VEC_UNPACKLU(rgbg3);
194 
195       /* (Original)
196        * Y  =  0.29900 * R + 0.58700 * G + 0.11400 * B
197        * Cb = -0.16874 * R - 0.33126 * G + 0.50000 * B + CENTERJSAMPLE
198        * Cr =  0.50000 * R - 0.41869 * G - 0.08131 * B + CENTERJSAMPLE
199        *
200        * (This implementation)
201        * Y  =  0.29900 * R + 0.33700 * G + 0.11400 * B + 0.25000 * G
202        * Cb = -0.16874 * R - 0.33126 * G + 0.50000 * B + CENTERJSAMPLE
203        * Cr =  0.50000 * R - 0.41869 * G - 0.08131 * B + CENTERJSAMPLE
204        */
205 
206       /* Calculate Y values */
207 
208       y0 = vec_msums(rg0, pw_f0299_f0337, pd_onehalf);
209       y1 = vec_msums(rg1, pw_f0299_f0337, pd_onehalf);
210       y2 = vec_msums(rg2, pw_f0299_f0337, pd_onehalf);
211       y3 = vec_msums(rg3, pw_f0299_f0337, pd_onehalf);
212       y0 = vec_msums(bg0, pw_f0114_f0250, y0);
213       y1 = vec_msums(bg1, pw_f0114_f0250, y1);
214       y2 = vec_msums(bg2, pw_f0114_f0250, y2);
215       y3 = vec_msums(bg3, pw_f0114_f0250, y3);
216       /* Clever way to avoid 4 shifts + 2 packs.  This packs the high word from
217        * each dword into a new 16-bit vector, which is the equivalent of
218        * descaling the 32-bit results (right-shifting by 16 bits) and then
219        * packing them.
220        */
221       yl = vec_perm((__vector unsigned short)y0, (__vector unsigned short)y1,
222                     shift_pack_index);
223       yh = vec_perm((__vector unsigned short)y2, (__vector unsigned short)y3,
224                     shift_pack_index);
225       y = vec_pack(yl, yh);
226       vec_st(y, 0, outptr0);
227 
228       /* Calculate Cb values */
229       cb0 = vec_msums(rg0, pw_mf016_mf033, pd_onehalfm1_cj);
230       cb1 = vec_msums(rg1, pw_mf016_mf033, pd_onehalfm1_cj);
231       cb2 = vec_msums(rg2, pw_mf016_mf033, pd_onehalfm1_cj);
232       cb3 = vec_msums(rg3, pw_mf016_mf033, pd_onehalfm1_cj);
233       cb0 = (__vector int)vec_msum((__vector unsigned short)bg0, pw_f050_f000,
234                                    (__vector unsigned int)cb0);
235       cb1 = (__vector int)vec_msum((__vector unsigned short)bg1, pw_f050_f000,
236                                    (__vector unsigned int)cb1);
237       cb2 = (__vector int)vec_msum((__vector unsigned short)bg2, pw_f050_f000,
238                                    (__vector unsigned int)cb2);
239       cb3 = (__vector int)vec_msum((__vector unsigned short)bg3, pw_f050_f000,
240                                    (__vector unsigned int)cb3);
241       cbl = vec_perm((__vector unsigned short)cb0,
242                      (__vector unsigned short)cb1, shift_pack_index);
243       cbh = vec_perm((__vector unsigned short)cb2,
244                      (__vector unsigned short)cb3, shift_pack_index);
245       cb = vec_pack(cbl, cbh);
246       vec_st(cb, 0, outptr1);
247 
248       /* Calculate Cr values */
249       cr0 = vec_msums(bg0, pw_mf008_mf041, pd_onehalfm1_cj);
250       cr1 = vec_msums(bg1, pw_mf008_mf041, pd_onehalfm1_cj);
251       cr2 = vec_msums(bg2, pw_mf008_mf041, pd_onehalfm1_cj);
252       cr3 = vec_msums(bg3, pw_mf008_mf041, pd_onehalfm1_cj);
253       cr0 = (__vector int)vec_msum((__vector unsigned short)rg0, pw_f050_f000,
254                                    (__vector unsigned int)cr0);
255       cr1 = (__vector int)vec_msum((__vector unsigned short)rg1, pw_f050_f000,
256                                    (__vector unsigned int)cr1);
257       cr2 = (__vector int)vec_msum((__vector unsigned short)rg2, pw_f050_f000,
258                                    (__vector unsigned int)cr2);
259       cr3 = (__vector int)vec_msum((__vector unsigned short)rg3, pw_f050_f000,
260                                    (__vector unsigned int)cr3);
261       crl = vec_perm((__vector unsigned short)cr0,
262                      (__vector unsigned short)cr1, shift_pack_index);
263       crh = vec_perm((__vector unsigned short)cr2,
264                      (__vector unsigned short)cr3, shift_pack_index);
265       cr = vec_pack(crl, crh);
266       vec_st(cr, 0, outptr2);
267     }
268   }
269 }
270