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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 = {0,1,4,5,8,9,12,13,16,17,20,21,24,25,28,29};
61 #else
62     shift_pack_index = {2,3,6,7,10,11,14,15,18,19,22,23,26,27,30,31};
63 #endif
64 
65   while (--num_rows >= 0) {
66     inptr = *input_buf++;
67     outptr0 = output_buf[0][output_row];
68     outptr1 = output_buf[1][output_row];
69     outptr2 = output_buf[2][output_row];
70     output_row++;
71 
72     for (num_cols = pitch; num_cols > 0;
73          num_cols -= RGB_PIXELSIZE * 16, inptr += RGB_PIXELSIZE * 16,
74          outptr0 += 16, outptr1 += 16, outptr2 += 16) {
75 
76 #if __BIG_ENDIAN__
77       /* Load 16 pixels == 48 or 64 bytes */
78       offset = (size_t)inptr & 15;
79       if (offset) {
80         __vector unsigned char unaligned_shift_index;
81         int bytes = num_cols + offset;
82 
83         if (bytes < (RGB_PIXELSIZE + 1) * 16 && (bytes & 15)) {
84           /* Slow path to prevent buffer overread.  Since there is no way to
85            * read a partial AltiVec register, overread would occur on the last
86            * chunk of the last image row if the right edge is not on a 16-byte
87            * boundary.  It could also occur on other rows if the bytes per row
88            * is low enough.  Since we can't determine whether we're on the last
89            * image row, we have to assume every row is the last.
90            */
91           memcpy(tmpbuf, inptr, min(num_cols, RGB_PIXELSIZE * 16));
92           rgb0 = vec_ld(0, tmpbuf);
93           rgb1 = vec_ld(16, tmpbuf);
94           rgb2 = vec_ld(32, tmpbuf);
95 #if RGB_PIXELSIZE == 4
96           rgb3 = vec_ld(48, tmpbuf);
97 #endif
98         } else {
99           /* Fast path */
100           rgb0 = vec_ld(0, inptr);
101           if (bytes > 16)
102             rgb1 = vec_ld(16, inptr);
103           if (bytes > 32)
104             rgb2 = vec_ld(32, inptr);
105           if (bytes > 48)
106             rgb3 = vec_ld(48, inptr);
107 #if RGB_PIXELSIZE == 4
108           if (bytes > 64)
109             rgb4 = vec_ld(64, inptr);
110 #endif
111           unaligned_shift_index = vec_lvsl(0, inptr);
112           rgb0 = vec_perm(rgb0, rgb1, unaligned_shift_index);
113           rgb1 = vec_perm(rgb1, rgb2, unaligned_shift_index);
114           rgb2 = vec_perm(rgb2, rgb3, unaligned_shift_index);
115 #if RGB_PIXELSIZE == 4
116           rgb3 = vec_perm(rgb3, rgb4, unaligned_shift_index);
117 #endif
118         }
119       } else {
120 #endif /* __BIG_ENDIAN__ */
121         if (num_cols < RGB_PIXELSIZE * 16 && (num_cols & 15)) {
122           /* Slow path */
123           memcpy(tmpbuf, inptr, min(num_cols, RGB_PIXELSIZE * 16));
124           rgb0 = VEC_LD(0, tmpbuf);
125           rgb1 = VEC_LD(16, tmpbuf);
126           rgb2 = VEC_LD(32, tmpbuf);
127 #if RGB_PIXELSIZE == 4
128           rgb3 = VEC_LD(48, tmpbuf);
129 #endif
130         } else {
131           /* Fast path */
132           rgb0 = VEC_LD(0, inptr);
133           if (num_cols > 16)
134             rgb1 = VEC_LD(16, inptr);
135           if (num_cols > 32)
136             rgb2 = VEC_LD(32, inptr);
137 #if RGB_PIXELSIZE == 4
138           if (num_cols > 48)
139             rgb3 = VEC_LD(48, inptr);
140 #endif
141         }
142 #if __BIG_ENDIAN__
143       }
144 #endif
145 
146 #if RGB_PIXELSIZE == 3
147       /* rgb0 = R0 G0 B0 R1 G1 B1 R2 G2 B2 R3 G3 B3 R4 G4 B4 R5
148        * rgb1 = G5 B5 R6 G6 B6 R7 G7 B7 R8 G8 B8 R9 G9 B9 Ra Ga
149        * rgb2 = Ba Rb Gb Bb Rc Gc Bc Rd Gd Bd Re Ge Be Rf Gf Bf
150        *
151        * rgbg0 = R0 G0 R1 G1 R2 G2 R3 G3 B0 G0 B1 G1 B2 G2 B3 G3
152        * rgbg1 = R4 G4 R5 G5 R6 G6 R7 G7 B4 G4 B5 G5 B6 G6 B7 G7
153        * rgbg2 = R8 G8 R9 G9 Ra Ga Rb Gb B8 G8 B9 G9 Ba Ga Bb Gb
154        * rgbg3 = Rc Gc Rd Gd Re Ge Rf Gf Bc Gc Bd Gd Be Ge Bf Gf
155        */
156       rgbg0 = vec_perm(rgb0, rgb0, (__vector unsigned char)RGBG_INDEX0);
157       rgbg1 = vec_perm(rgb0, rgb1, (__vector unsigned char)RGBG_INDEX1);
158       rgbg2 = vec_perm(rgb1, rgb2, (__vector unsigned char)RGBG_INDEX2);
159       rgbg3 = vec_perm(rgb2, rgb2, (__vector unsigned char)RGBG_INDEX3);
160 #else
161       /* rgb0 = R0 G0 B0 X0 R1 G1 B1 X1 R2 G2 B2 X2 R3 G3 B3 X3
162        * rgb1 = R4 G4 B4 X4 R5 G5 B5 X5 R6 G6 B6 X6 R7 G7 B7 X7
163        * rgb2 = R8 G8 B8 X8 R9 G9 B9 X9 Ra Ga Ba Xa Rb Gb Bb Xb
164        * rgb3 = Rc Gc Bc Xc Rd Gd Bd Xd Re Ge Be Xe Rf Gf Bf Xf
165        *
166        * rgbg0 = R0 G0 R1 G1 R2 G2 R3 G3 B0 G0 B1 G1 B2 G2 B3 G3
167        * rgbg1 = R4 G4 R5 G5 R6 G6 R7 G7 B4 G4 B5 G5 B6 G6 B7 G7
168        * rgbg2 = R8 G8 R9 G9 Ra Ga Rb Gb B8 G8 B9 G9 Ba Ga Bb Gb
169        * rgbg3 = Rc Gc Rd Gd Re Ge Rf Gf Bc Gc Bd Gd Be Ge Bf Gf
170        */
171       rgbg0 = vec_perm(rgb0, rgb0, (__vector unsigned char)RGBG_INDEX);
172       rgbg1 = vec_perm(rgb1, rgb1, (__vector unsigned char)RGBG_INDEX);
173       rgbg2 = vec_perm(rgb2, rgb2, (__vector unsigned char)RGBG_INDEX);
174       rgbg3 = vec_perm(rgb3, rgb3, (__vector unsigned char)RGBG_INDEX);
175 #endif
176 
177       /* rg0 = R0 G0 R1 G1 R2 G2 R3 G3
178        * bg0 = B0 G0 B1 G1 B2 G2 B3 G3
179        * ...
180        *
181        * NOTE: We have to use vec_merge*() here because vec_unpack*() doesn't
182        * support unsigned vectors.
183        */
184       rg0 = (__vector signed short)VEC_UNPACKHU(rgbg0);
185       bg0 = (__vector signed short)VEC_UNPACKLU(rgbg0);
186       rg1 = (__vector signed short)VEC_UNPACKHU(rgbg1);
187       bg1 = (__vector signed short)VEC_UNPACKLU(rgbg1);
188       rg2 = (__vector signed short)VEC_UNPACKHU(rgbg2);
189       bg2 = (__vector signed short)VEC_UNPACKLU(rgbg2);
190       rg3 = (__vector signed short)VEC_UNPACKHU(rgbg3);
191       bg3 = (__vector signed short)VEC_UNPACKLU(rgbg3);
192 
193       /* (Original)
194        * Y  =  0.29900 * R + 0.58700 * G + 0.11400 * B
195        * Cb = -0.16874 * R - 0.33126 * G + 0.50000 * B + CENTERJSAMPLE
196        * Cr =  0.50000 * R - 0.41869 * G - 0.08131 * B + CENTERJSAMPLE
197        *
198        * (This implementation)
199        * Y  =  0.29900 * R + 0.33700 * G + 0.11400 * B + 0.25000 * G
200        * Cb = -0.16874 * R - 0.33126 * G + 0.50000 * B + CENTERJSAMPLE
201        * Cr =  0.50000 * R - 0.41869 * G - 0.08131 * B + CENTERJSAMPLE
202        */
203 
204       /* Calculate Y values */
205 
206       y0 = vec_msums(rg0, pw_f0299_f0337, pd_onehalf);
207       y1 = vec_msums(rg1, pw_f0299_f0337, pd_onehalf);
208       y2 = vec_msums(rg2, pw_f0299_f0337, pd_onehalf);
209       y3 = vec_msums(rg3, pw_f0299_f0337, pd_onehalf);
210       y0 = vec_msums(bg0, pw_f0114_f0250, y0);
211       y1 = vec_msums(bg1, pw_f0114_f0250, y1);
212       y2 = vec_msums(bg2, pw_f0114_f0250, y2);
213       y3 = vec_msums(bg3, pw_f0114_f0250, y3);
214       /* Clever way to avoid 4 shifts + 2 packs.  This packs the high word from
215        * each dword into a new 16-bit vector, which is the equivalent of
216        * descaling the 32-bit results (right-shifting by 16 bits) and then
217        * packing them.
218        */
219       yl = vec_perm((__vector unsigned short)y0, (__vector unsigned short)y1,
220                     shift_pack_index);
221       yh = vec_perm((__vector unsigned short)y2, (__vector unsigned short)y3,
222                     shift_pack_index);
223       y = vec_pack(yl, yh);
224       vec_st(y, 0, outptr0);
225 
226       /* Calculate Cb values */
227       cb0 = vec_msums(rg0, pw_mf016_mf033, pd_onehalfm1_cj);
228       cb1 = vec_msums(rg1, pw_mf016_mf033, pd_onehalfm1_cj);
229       cb2 = vec_msums(rg2, pw_mf016_mf033, pd_onehalfm1_cj);
230       cb3 = vec_msums(rg3, pw_mf016_mf033, pd_onehalfm1_cj);
231       cb0 = (__vector int)vec_msum((__vector unsigned short)bg0, pw_f050_f000,
232                                    (__vector unsigned int)cb0);
233       cb1 = (__vector int)vec_msum((__vector unsigned short)bg1, pw_f050_f000,
234                                    (__vector unsigned int)cb1);
235       cb2 = (__vector int)vec_msum((__vector unsigned short)bg2, pw_f050_f000,
236                                    (__vector unsigned int)cb2);
237       cb3 = (__vector int)vec_msum((__vector unsigned short)bg3, pw_f050_f000,
238                                    (__vector unsigned int)cb3);
239       cbl = vec_perm((__vector unsigned short)cb0,
240                      (__vector unsigned short)cb1, shift_pack_index);
241       cbh = vec_perm((__vector unsigned short)cb2,
242                      (__vector unsigned short)cb3, shift_pack_index);
243       cb = vec_pack(cbl, cbh);
244       vec_st(cb, 0, outptr1);
245 
246       /* Calculate Cr values */
247       cr0 = vec_msums(bg0, pw_mf008_mf041, pd_onehalfm1_cj);
248       cr1 = vec_msums(bg1, pw_mf008_mf041, pd_onehalfm1_cj);
249       cr2 = vec_msums(bg2, pw_mf008_mf041, pd_onehalfm1_cj);
250       cr3 = vec_msums(bg3, pw_mf008_mf041, pd_onehalfm1_cj);
251       cr0 = (__vector int)vec_msum((__vector unsigned short)rg0, pw_f050_f000,
252                                    (__vector unsigned int)cr0);
253       cr1 = (__vector int)vec_msum((__vector unsigned short)rg1, pw_f050_f000,
254                                    (__vector unsigned int)cr1);
255       cr2 = (__vector int)vec_msum((__vector unsigned short)rg2, pw_f050_f000,
256                                    (__vector unsigned int)cr2);
257       cr3 = (__vector int)vec_msum((__vector unsigned short)rg3, pw_f050_f000,
258                                    (__vector unsigned int)cr3);
259       crl = vec_perm((__vector unsigned short)cr0,
260                      (__vector unsigned short)cr1, shift_pack_index);
261       crh = vec_perm((__vector unsigned short)cr2,
262                      (__vector unsigned short)cr3, shift_pack_index);
263       cr = vec_pack(crl, crh);
264       vec_st(cr, 0, outptr2);
265     }
266   }
267 }
268