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video: fbdev: ssd1307fb: Simplify ssd1307fb_update_display()

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Simplify the nested loops to handle conversion from linear frame buffer
to ssd1307 page layout:
  1. Move last page handling one level up, as the value of "m" is the
     same inside a page,
  2. array->data[] is filled linearly, so there is no need to
     recalculate array_idx over and over again; a simple increment is
     sufficient.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210727134730.3765898-3-geert@linux-m68k.org
This commit is contained in:
Geert Uytterhoeven 2021-07-27 15:47:27 +02:00 committed by Sam Ravnborg
parent 7b4b3733fd
commit ef9d793825
1 changed files with 10 additions and 7 deletions
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17
drivers/video/fbdev/ssd1307fb.c
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@ -158,6 +158,7 @@ static int ssd1307fb_update_display(struct ssd1307fb_par *par)
u8 *vmem = par->info->screen_buffer;
unsigned int line_length = par->info->fix.line_length;
unsigned int pages = DIV_ROUND_UP(par->height, 8);
u32 array_idx = 0;
int ret, i, j, k;
array = ssd1307fb_alloc_array(par->width * pages, SSD1307FB_DATA);
@ -194,19 +195,21 @@ static int ssd1307fb_update_display(struct ssd1307fb_par *par)
*/
for (i = 0; i < pages; i++) {
int m = 8;
/* Last page may be partial */
if (i + 1 == pages && par->height % 8)
m = par->height % 8;
for (j = 0; j < par->width; j++) {
int m = 8;
u32 array_idx = i * par->width + j;
array->data[array_idx] = 0;
/* Last page may be partial */
if (i + 1 == pages && par->height % 8)
m = par->height % 8;
u8 data = 0;
for (k = 0; k < m; k++) {
u8 byte = vmem[(8 * i + k) * line_length +
j / 8];
u8 bit = (byte >> (j % 8)) & 1;
array->data[array_idx] |= bit << k;
data |= bit << k;
}
array->data[array_idx++] = data;
}
}