1
2 /* palette_neon_intrinsics.c - NEON optimised palette expansion functions
3 *
4 * Copyright (c) 2018-2019 Cosmin Truta
5 * Copyright (c) 2017-2018 Arm Holdings. All rights reserved.
6 * Written by Richard Townsend <Richard.Townsend@arm.com>, February 2017.
7 *
8 * This code is released under the libpng license.
9 * For conditions of distribution and use, see the disclaimer
10 * and license in png.h
11 */
12
13 #include "../pngpriv.h"
14
15 #if PNG_ARM_NEON_IMPLEMENTATION == 1
16
17 #if defined(_MSC_VER) && !defined(__clang__) && defined(_M_ARM64)
18 # include <arm64_neon.h>
19 #else
20 # include <arm_neon.h>
21 #endif
22
23 /* Build an RGBA8 palette from the separate RGB and alpha palettes. */
24 void
25 png_riffle_palette_neon(png_structrp png_ptr)
26 {
27 png_const_colorp palette = png_ptr->palette;
28 png_bytep riffled_palette = png_ptr->riffled_palette;
29 png_const_bytep trans_alpha = png_ptr->trans_alpha;
30 int num_trans = png_ptr->num_trans;
31 int i;
32
33 /* Initially black, opaque. */
34 uint8x16x4_t w = {{
35 vdupq_n_u8(0x00),
36 vdupq_n_u8(0x00),
37 vdupq_n_u8(0x00),
38 vdupq_n_u8(0xff),
39 }};
40
41 png_debug(1, "in png_riffle_palette_neon");
42
43 /* First, riffle the RGB colours into an RGBA8 palette.
44 * The alpha component is set to opaque for now.
45 */
46 for (i = 0; i < 256; i += 16)
47 {
48 uint8x16x3_t v = vld3q_u8((png_const_bytep)(palette + i));
49 w.val[0] = v.val[0];
50 w.val[1] = v.val[1];
51 w.val[2] = v.val[2];
52 vst4q_u8(riffled_palette + (i << 2), w);
53 }
54
55 /* Fix up the missing transparency values. */
56 for (i = 0; i < num_trans; i++)
57 riffled_palette[(i << 2) + 3] = trans_alpha[i];
58 }
59
60 /* Expands a palettized row into RGBA8. */
61 int
62 png_do_expand_palette_rgba8_neon(png_structrp png_ptr, png_row_infop row_info,
63 png_const_bytep row, png_bytepp ssp, png_bytepp ddp)
64 {
65 png_uint_32 row_width = row_info->width;
66 const png_uint_32 *riffled_palette =
67 (const png_uint_32 *)png_ptr->riffled_palette;
68 const png_uint_32 pixels_per_chunk = 4;
69 png_uint_32 i;
70
71 png_debug(1, "in png_do_expand_palette_rgba8_neon");
72
73 PNG_UNUSED(row)
74 if (row_width < pixels_per_chunk)
75 return 0;
76
77 /* This function originally gets the last byte of the output row.
78 * The NEON part writes forward from a given position, so we have
79 * to seek this back by 4 pixels x 4 bytes.
80 */
81 *ddp = *ddp - ((pixels_per_chunk * sizeof(png_uint_32)) - 1);
82
83 for (i = 0; i < row_width; i += pixels_per_chunk)
84 {
85 uint32x4_t cur;
86 png_bytep sp = *ssp - i, dp = *ddp - (i << 2);
87 cur = vld1q_dup_u32 (riffled_palette + *(sp - 3));
88 cur = vld1q_lane_u32(riffled_palette + *(sp - 2), cur, 1);
89 cur = vld1q_lane_u32(riffled_palette + *(sp - 1), cur, 2);
90 cur = vld1q_lane_u32(riffled_palette + *(sp - 0), cur, 3);
91 vst1q_u32((void *)dp, cur);
92 }
93 if (i != row_width)
94 {
95 /* Remove the amount that wasn't processed. */
96 i -= pixels_per_chunk;
97 }
98
99 /* Decrement output pointers. */
100 *ssp = *ssp - i;
101 *ddp = *ddp - (i << 2);
102 return i;
103 }
104
105 /* Expands a palettized row into RGB8. */
106 int
107 png_do_expand_palette_rgb8_neon(png_structrp png_ptr, png_row_infop row_info,
108 png_const_bytep row, png_bytepp ssp, png_bytepp ddp)
109 {
110 png_uint_32 row_width = row_info->width;
111 png_const_bytep palette = (png_const_bytep)png_ptr->palette;
112 const png_uint_32 pixels_per_chunk = 8;
113 png_uint_32 i;
114
115 png_debug(1, "in png_do_expand_palette_rgb8_neon");
116
117 PNG_UNUSED(row)
118 if (row_width <= pixels_per_chunk)
119 return 0;
120
121 /* Seeking this back by 8 pixels x 3 bytes. */
122 *ddp = *ddp - ((pixels_per_chunk * sizeof(png_color)) - 1);
123
124 for (i = 0; i < row_width; i += pixels_per_chunk)
125 {
126 uint8x8x3_t cur;
127 png_bytep sp = *ssp - i, dp = *ddp - ((i << 1) + i);
128 cur = vld3_dup_u8(palette + sizeof(png_color) * (*(sp - 7)));
129 cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 6)), cur, 1);
130 cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 5)), cur, 2);
131 cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 4)), cur, 3);
132 cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 3)), cur, 4);
133 cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 2)), cur, 5);
134 cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 1)), cur, 6);
135 cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 0)), cur, 7);
136 vst3_u8((void *)dp, cur);
137 }
138
139 if (i != row_width)
140 {
141 /* Remove the amount that wasn't processed. */
142 i -= pixels_per_chunk;
143 }
144
145 /* Decrement output pointers. */
146 *ssp = *ssp - i;
147 *ddp = *ddp - ((i << 1) + i);
148 return i;
149 }
150
151 #endif /* PNG_ARM_NEON_IMPLEMENTATION */