1 /* SPDX-License-Identifier: GPL-2.0-only 2 * 3 * Generic bit area filler and twister engine for packed pixel framebuffers 4 * 5 * Rewritten by: 6 * Copyright (C) 2025 Zsolt Kajtar (soci@c64.rulez.org) 7 * 8 * Based on earlier work of: 9 * Copyright (C) 2000 James Simmons (jsimmons@linux-fbdev.org) 10 * Michal Januszewski <spock@gentoo.org> 11 * Anton Vorontsov <avorontsov@ru.mvista.com> 12 * Pavel Pisa <pisa@cmp.felk.cvut.cz> 13 * Antonino A. Daplas <adaplas@gmail.com> 14 * Geert Uytterhoeven 15 * and others 16 * 17 * NOTES: 18 * 19 * Handles native and foreign byte order on both endians, standard and 20 * reverse pixel order in a byte (<8 BPP), word length of 32/64 bits, 21 * bits per pixel from 1 to the word length. Handles line lengths at byte 22 * granularity while maintaining aligned accesses. 23 * 24 * Optimized path for power of two bits per pixel modes. 25 */ 26 #include "fb_draw.h" 27 28 /* inverts bits at a given offset */ 29 static inline void fb_invert_offset(unsigned long pat, int offset, const struct fb_address *dst) 30 { 31 fb_write_offset(fb_read_offset(offset, dst) ^ pat, offset, dst); 32 } 33 34 /* state for pattern generator and whether swapping is necessary */ 35 struct fb_pattern { 36 unsigned long pixels; 37 int left, right; 38 struct fb_reverse reverse; 39 }; 40 41 /* used to get the pattern in native order */ 42 static unsigned long fb_pattern_get(struct fb_pattern *pattern) 43 { 44 return pattern->pixels; 45 } 46 47 /* used to get the pattern in reverse order */ 48 static unsigned long fb_pattern_get_reverse(struct fb_pattern *pattern) 49 { 50 return swab_long(pattern->pixels); 51 } 52 53 /* next static pattern */ 54 static void fb_pattern_static(struct fb_pattern *pattern) 55 { 56 /* nothing to do */ 57 } 58 59 /* next rotating pattern */ 60 static void fb_pattern_rotate(struct fb_pattern *pattern) 61 { 62 pattern->pixels = fb_left(pattern->pixels, pattern->left) 63 | fb_right(pattern->pixels, pattern->right); 64 } 65 66 #define FB_PAT(i) (((1UL<<(BITS_PER_LONG-1)/(i)*(i))/((1<<(i))-1)<<(i))|1) 67 68 /* create the filling pattern from a given color */ 69 static unsigned long pixel_to_pat(int bpp, u32 color) 70 { 71 static const unsigned long mulconst[BITS_PER_LONG/4] = { 72 0, ~0UL, FB_PAT(2), FB_PAT(3), 73 FB_PAT(4), FB_PAT(5), FB_PAT(6), FB_PAT(7), 74 #if BITS_PER_LONG == 64 75 FB_PAT(8), FB_PAT(9), FB_PAT(10), FB_PAT(11), 76 FB_PAT(12), FB_PAT(13), FB_PAT(14), FB_PAT(15), 77 #endif 78 }; 79 unsigned long pattern; 80 81 switch (bpp) { 82 case 0 ... BITS_PER_LONG/4-1: 83 pattern = mulconst[bpp] * color; 84 break; 85 case BITS_PER_LONG/4 ... BITS_PER_LONG/2-1: 86 pattern = color; 87 pattern = pattern | pattern << bpp; 88 pattern = pattern | pattern << bpp*2; 89 break; 90 case BITS_PER_LONG/2 ... BITS_PER_LONG-1: 91 pattern = color; 92 pattern = pattern | pattern << bpp; 93 break; 94 default: 95 return color; 96 } 97 #ifndef __LITTLE_ENDIAN 98 pattern <<= (BITS_PER_LONG % bpp); 99 pattern |= pattern >> bpp; 100 #endif 101 return pattern; 102 } 103 104 /* overwrite bits according to a pattern in a line */ 105 static __always_inline void bitfill(const struct fb_address *dst, 106 struct fb_pattern *pattern, 107 unsigned long (*get)(struct fb_pattern *pattern), 108 void (*rotate)(struct fb_pattern *pattern), 109 int end) 110 { 111 unsigned long first, last; 112 113 end += dst->bits; 114 first = fb_pixel_mask(dst->bits, pattern->reverse); 115 last = ~fb_pixel_mask(end & (BITS_PER_LONG-1), pattern->reverse); 116 117 if (end <= BITS_PER_LONG) { 118 last = last ? (last & first) : first; 119 first = get(pattern); 120 if (last == ~0UL) 121 fb_write_offset(first, 0, dst); 122 else if (last) 123 fb_modify_offset(first, last, 0, dst); 124 } else { 125 int offset = first != ~0UL; 126 127 if (offset) { 128 fb_modify_offset(get(pattern), first, 0, dst); 129 rotate(pattern); 130 } 131 end /= BITS_PER_LONG; 132 for (; offset + 4 <= end; offset += 4) { 133 fb_write_offset(get(pattern), offset + 0, dst); 134 rotate(pattern); 135 fb_write_offset(get(pattern), offset + 1, dst); 136 rotate(pattern); 137 fb_write_offset(get(pattern), offset + 2, dst); 138 rotate(pattern); 139 fb_write_offset(get(pattern), offset + 3, dst); 140 rotate(pattern); 141 } 142 while (offset < end) { 143 fb_write_offset(get(pattern), offset++, dst); 144 rotate(pattern); 145 } 146 147 if (last) 148 fb_modify_offset(get(pattern), last, offset, dst); 149 } 150 } 151 152 /* inverts bits according to a pattern in a line */ 153 static __always_inline void bitinvert(const struct fb_address *dst, 154 struct fb_pattern *pattern, 155 unsigned long (*get)(struct fb_pattern *pattern), 156 void (*rotate)(struct fb_pattern *pattern), 157 int end) 158 { 159 unsigned long first, last; 160 int offset; 161 162 end += dst->bits; 163 first = fb_pixel_mask(dst->bits, pattern->reverse); 164 last = ~fb_pixel_mask(end & (BITS_PER_LONG-1), pattern->reverse); 165 166 if (end <= BITS_PER_LONG) { 167 offset = 0; 168 last = last ? (last & first) : first; 169 } else { 170 offset = first != ~0UL; 171 172 if (offset) { 173 first &= get(pattern); 174 if (first) 175 fb_invert_offset(first, 0, dst); 176 rotate(pattern); 177 } 178 179 end /= BITS_PER_LONG; 180 for (; offset + 4 <= end; offset += 4) { 181 fb_invert_offset(get(pattern), offset + 0, dst); 182 rotate(pattern); 183 fb_invert_offset(get(pattern), offset + 1, dst); 184 rotate(pattern); 185 fb_invert_offset(get(pattern), offset + 2, dst); 186 rotate(pattern); 187 fb_invert_offset(get(pattern), offset + 3, dst); 188 rotate(pattern); 189 } 190 while (offset < end) { 191 fb_invert_offset(get(pattern), offset++, dst); 192 rotate(pattern); 193 } 194 } 195 196 last &= get(pattern); 197 if (last) 198 fb_invert_offset(last, offset, dst); 199 } 200 201 /* pattern doesn't change. 1, 2, 4, 8, 16, 32, 64 bpp */ 202 static inline void fb_fillrect_static(const struct fb_fillrect *rect, int bpp, 203 struct fb_address *dst, struct fb_pattern *pattern, 204 unsigned int bits_per_line) 205 { 206 u32 height = rect->height; 207 int width = rect->width * bpp; 208 209 if (bpp > 8 && pattern->reverse.byte) 210 pattern->pixels = swab_long(pattern->pixels); 211 212 if (rect->rop == ROP_XOR) 213 while (height--) { 214 bitinvert(dst, pattern, fb_pattern_get, fb_pattern_static, width); 215 fb_address_forward(dst, bits_per_line); 216 } 217 else 218 while (height--) { 219 bitfill(dst, pattern, fb_pattern_get, fb_pattern_static, width); 220 fb_address_forward(dst, bits_per_line); 221 } 222 } 223 224 /* rotate pattern to the correct position */ 225 static inline unsigned long fb_rotate(unsigned long pattern, int shift, int bpp) 226 { 227 shift %= bpp; 228 return fb_right(pattern, shift) | fb_left(pattern, bpp - shift); 229 } 230 231 /* rotating pattern, for example 24 bpp */ 232 static __always_inline void fb_fillrect_rotating(const struct fb_fillrect *rect, 233 int bpp, struct fb_address *dst, 234 struct fb_pattern *pattern, 235 unsigned long (*get)(struct fb_pattern *pattern), 236 unsigned int bits_per_line) 237 { 238 unsigned long pat = pattern->pixels; 239 u32 height = rect->height; 240 int width = rect->width * bpp; 241 242 if (rect->rop == ROP_XOR) 243 while (height--) { 244 pattern->pixels = fb_rotate(pat, dst->bits, bpp); 245 bitinvert(dst, pattern, get, fb_pattern_rotate, width); 246 fb_address_forward(dst, bits_per_line); 247 } 248 else 249 while (height--) { 250 pattern->pixels = fb_rotate(pat, dst->bits, bpp); 251 bitfill(dst, pattern, get, fb_pattern_rotate, width); 252 fb_address_forward(dst, bits_per_line); 253 } 254 } 255 256 static inline void fb_fillrect(struct fb_info *p, const struct fb_fillrect *rect) 257 { 258 int bpp = p->var.bits_per_pixel; 259 unsigned int bits_per_line = BYTES_TO_BITS(p->fix.line_length); 260 const u32 *palette = fb_palette(p); 261 struct fb_address dst = fb_address_init(p); 262 struct fb_pattern pattern; 263 264 fb_address_forward(&dst, rect->dy * bits_per_line + rect->dx * bpp); 265 266 pattern.pixels = pixel_to_pat(bpp, palette ? palette[rect->color] : rect->color); 267 pattern.reverse = fb_reverse_init(p); 268 pattern.left = BITS_PER_LONG % bpp; 269 if (pattern.left) { 270 pattern.right = bpp - pattern.left; 271 if (pattern.reverse.byte) 272 fb_fillrect_rotating(rect, bpp, &dst, &pattern, 273 fb_pattern_get_reverse, bits_per_line); 274 else 275 fb_fillrect_rotating(rect, bpp, &dst, &pattern, 276 fb_pattern_get, bits_per_line); 277 } else 278 fb_fillrect_static(rect, bpp, &dst, &pattern, bits_per_line); 279 } 280