Performance improvements for runtime icon generation.

As most of the rows for any given icon tile are the same as the
previously-generated row, it is not necessary to recompute the
colour values every single time.  The code can be adjusted to
re-use the previously-computed row instead.

Since the generic code now works on bytes, we can also replace the
open-coded loops in the row generation with a couple of memset calls,
which should help modern compilers produce more efficient output.

All this reduces the amount of computation done by the generic code
substantially, to roughly a quarter of what it was previously.

Also take the time to remove some unneeded complexity in the EWMH
formatting implementation, which further helps a little bit on the
code size front.

diff --git a/src/ewmhicon.c b/src/ewmhicon.c
index 319ed3ac548e746c9df3e92f9a850cf3774a78ae..7e69ec883f5c36317c900abff0a947e03b149d8c 100644 (file)
--- a/src/ewmhicon.c
+++ b/src/ewmhicon.c
@@ -1,6 +1,6 @@
 /*
  * _NET_WM_ICON helpers for slide puzzle game
- * Copyright © 2022 Nick Bowler
+ * Copyright © 2022-2023 Nick Bowler
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -32,41 +32,6 @@
 
 enum { ICON_16x16, ICON_24x24, ICON_32x32, ICON_48x48, ICON_MAX };
 
-/*
- * Allocate storage for the EWMH _NET_WM_ICON array.  The sizes array is
- * populated with pointers to the beginning of each icon's pixel data.  For
- * example, sizes[ICON_24x24] points to the first pixel of the 24x24 image.
- *
- * The returned value can then be passed to XChangeProperty to set the icon,
- * (use EWMH_ICON_NELEM for the number of elements) and must be freed by the
- * caller.
- */
-static void *ewmh_icon_alloc(unsigned long **sizes)
-{
-       unsigned long *buf;
-
-       buf = calloc(sizeof *buf, EWMH_ICON_NELEM);
-       if (buf) {
-               sizes[ICON_16x16] = buf;
-               *sizes[ICON_16x16]++ = 16;
-               *sizes[ICON_16x16]++ = 16;
-
-               sizes[ICON_24x24] = sizes[ICON_16x16] + 16*16;
-               *sizes[ICON_24x24]++ = 24;
-               *sizes[ICON_24x24]++ = 24;
-
-               sizes[ICON_32x32] = sizes[ICON_24x24] + 24*24;
-               *sizes[ICON_32x32]++ = 32;
-               *sizes[ICON_32x32]++ = 32;
-
-               sizes[ICON_48x48] = sizes[ICON_32x32] + 32*32;
-               *sizes[ICON_48x48]++ = 48;
-               *sizes[ICON_48x48]++ = 48;
-       }
-
-       return buf;
-}
-
 static unsigned long scale16to8(unsigned x)
 {
        return x*0xfful / 0xffff;
@@ -80,43 +45,51 @@ static unsigned long wm_pixel(const XColor *c)
             | scale16to8(c->blue);
 }
 
-static void do_remap(void *icon, unsigned size, const XColor *map)
+static void do_remap(void *icon, unsigned area, const XColor *map)
 {
        unsigned char *index = icon;
        unsigned long *argb = icon;
-       unsigned i, count = size*size;
+       unsigned i;
 
-       for (i = 0; i < count; i++) {
-               argb[count-i-1] = wm_pixel(map + index[count-i-1]);
+       area--;
+       for (i = 0; i <= area; i++) {
+               argb[area-i] = wm_pixel(map + index[area-i]);
        }
 }
 
 void *ewmh_icon_generate(const unsigned long *seq, const XColor *map)
 {
-       unsigned long *buf, *sizes[ICON_MAX];
-       unsigned i, j;
+       static const unsigned char dims[ICON_MAX] = { 16, 24, 32, 48 };
+       unsigned long *work, *ret;
+       unsigned i, j, fullsize, size;
 
-       buf = ewmh_icon_alloc(sizes);
-       if (!buf)
+       work = ret = malloc(sizeof *work * EWMH_ICON_NELEM);
+       if (!work)
                return NULL;
 
-       for (i = 0; i < 9; i++) {
-               unsigned x = i%3, y = i/3;
+       for (i = fullsize = 0; i < ICON_MAX; i++) {
+               work += fullsize;
 
-               icon_tile16((void *)sizes[ICON_16x16], seq[i], x, y);
-               icon_tile24((void *)sizes[ICON_24x24], seq[i], x, y);
-               icon_tile32((void *)sizes[ICON_32x32], seq[i], x, y);
-               icon_tile48((void *)sizes[ICON_48x48], seq[i], x, y);
-       }
+               size = dims[i];
+               *work++ = size;
+               *work++ = size;
+
+               for (j = 0; j < 9; j++) {
+                       unsigned x = j%3, y = j/3;
 
-       for (i = 0; i < ICON_MAX; i++) {
-               /* Produces the sequence 16, 24, 32, 48 */
-               unsigned size = 16 + (1u<<i)/2 * 8;
+                       switch (i) {
+                       case 0: icon_tile16((void *)work, seq[j], x, y); break;
+                       case 1: icon_tile24((void *)work, seq[j], x, y); break;
+                       case 2: icon_tile32((void *)work, seq[j], x, y); break;
+                       case 3: icon_tile48((void *)work, seq[j], x, y); break;
+                       }
+               }
 
-               do_remap(sizes[i], size, map);
+               fullsize = size*size;
+               do_remap(work, fullsize, map);
        }
 
-       return buf;
+       return ret;
 }
 
 #if !X_DISPLAY_MISSING

diff --git a/src/icon.c b/src/icon.c
index 4970694c1abca950ebdc4da91029e2a5e8585c4d..4ea355b49e2c8c630ba43410396712546f2a82a9 100644 (file)
--- a/src/icon.c
+++ b/src/icon.c
@@ -1,6 +1,6 @@
 /*
  * Icon generation helpers for slide puzzle game
- * Copyright © 2022 Nick Bowler
+ * Copyright © 2022-2023 Nick Bowler
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -22,17 +22,29 @@
 #include "colour.h"
 #include "icon.h"
 
-static void format_row(unsigned char *row, unsigned long c,
-                       unsigned s, unsigned y, unsigned w, unsigned h)
+#define MIN(a, b) ((a) < (b) ? (a) : (b))
+
+#define primary(c) (((c) >> 8*COLOUR_PRIMARY) & 0xff)
+#define dark(c)    (((c) >> 8*COLOUR_DARK) & 0xff)
+#define light(c)   (((c) >> 8*COLOUR_LIGHT) & 0xff)
+
+static void format_row(unsigned char *row, unsigned long c, unsigned s,
+                       unsigned y, unsigned w, unsigned h)
+{
+       memset(row, dark(c), w);
+       memset(row, primary(c), y+s < h ? w-s : 0);
+       memset(row, light(c), y >= s ? MIN(s, h-y) : w-y);
+}
+
+static void format_row2(unsigned char *row, unsigned long c, unsigned s,
+                        unsigned y, unsigned w, unsigned h, unsigned stride)
 {
-       unsigned x;
-
-       for (x = 0; x < w; x++) {
-               row[x] = (c >> 8*COLOUR_PRIMARY) & 0xff;
-               if (x < s || y < s)
-                       row[x] = (c >> 8*COLOUR_LIGHT) & 0xff;
-               if ((x+s >= w && x+y >= w) || (y+s >= h && x+y >= h))
-                       row[x] = (c >> 8*COLOUR_DARK) & 0xff;
+       row += stride*y;
+       if (y > s && y+s < h) {
+               if (stride)
+                       memcpy(row, row-stride, w);
+       } else {
+               format_row(row, c, s, y, w, h);
        }
 }
 
@@ -42,16 +54,15 @@ static void format_row(unsigned char *row, unsigned long c,
  */
 void icon_tile16(unsigned char *icon, unsigned long c, int tile_x, int tile_y)
 {
-       int out_x, out_y, out_w, y;
        unsigned char row[6];
+       unsigned y, w;
 
-       out_x = tile_x * 11 / 2;
-       out_y = tile_y * 11 / 2;
-       out_w = (5 + (tile_x == 1)) * sizeof row[0];
+       icon += 16*(11u*tile_y / 2) + (11u*tile_x / 2);
 
-       for (y = 0+(tile_y == 0); y < 6-(tile_y == 2); y++) {
-               format_row(row, c, 1, y, 6, 6);
-               memcpy(&icon[16 * out_y++ + out_x], &row[tile_x == 0], out_w);
+       w = 5+(tile_x&1u);
+       for (y = !tile_y; y < 6-(tile_y==2); y++) {
+               format_row2(row, c, 1, y, 6, 6, 0);
+               memcpy(&icon[16*(y-!tile_y)], &row[!tile_x], w);
        }
 }
 
@@ -60,13 +71,12 @@ void icon_tile16(unsigned char *icon, unsigned long c, int tile_x, int tile_y)
  */
 void icon_tile24(unsigned char *icon, unsigned long c, int tile_x, int tile_y)
 {
-       int out_x, out_y, y;
+       unsigned y;
 
-       out_x = tile_x * 8;
-       out_y = tile_y * 8;
+       icon += 8*(24u*tile_y + tile_x);
 
        for (y = 0; y < 8; y++) {
-               format_row(&icon[24 * out_y++ + out_x], c, 1, y, 8, 8);
+               format_row2(icon, c, 1, y, 8, 8, 24);
        }
 }
 
@@ -76,15 +86,14 @@ void icon_tile24(unsigned char *icon, unsigned long c, int tile_x, int tile_y)
  */
 void icon_tile32(unsigned char *icon, unsigned long c, int tile_x, int tile_y)
 {
-       int out_x, out_y, out_w, out_h, y;
+       unsigned y, w, h;
 
-       out_x = 10*tile_x + (tile_x > 0);
-       out_y = 10*tile_y + (tile_y > 0);
-       out_w = 10 + (tile_x != 1);
-       out_h = 10 + (tile_y != 1);
+       icon += 32*(10u*tile_y + !!tile_y) + (10u*tile_x + !!tile_x);
 
-       for (y = 0; y < out_h; y++) {
-               format_row(&icon[32 * out_y++ + out_x], c, 1, y, out_w, out_h);
+       w = 10u + (tile_x != 1);
+       h = 10u + (tile_y != 1);
+       for (y = 0; y < h; y++) {
+               format_row2(icon, c, 1, y, w, h, 32);
        }
 }
 
@@ -93,12 +102,11 @@ void icon_tile32(unsigned char *icon, unsigned long c, int tile_x, int tile_y)
  */
 void icon_tile48(unsigned char *icon, unsigned long c, int tile_x, int tile_y)
 {
-       int out_x, out_y, y;
+       unsigned y;
 
-       out_x = tile_x * 16;
-       out_y = tile_y * 16;
+       icon += 16*(48u*tile_y + tile_x);
 
        for (y = 0; y < 16; y++) {
-               format_row(&icon[48 * out_y++ + out_x], c, 2, y, 16, 16);
+               format_row2(icon, c, 2, y, 16, 16, 48);
        }
 }