/* * Code adapted from uClibc-0.9.30.3 * * It is therefore covered by the GNU LESSER GENERAL PUBLIC LICENSE * Version 2.1, February 1999 * * Wolfgang Denk */ /* This code is derived from a public domain shell sort routine by * Ray Gardner and found in Bob Stout's snippets collection. The * original code is included below in an #if 0/#endif block. * * I modified it to avoid the possibility of overflow in the wgap * calculation, as well as to reduce the generated code size with * bcc and gcc. */ #include #if 0 #include #else #define assert(arg) #endif void qsort(void *base, size_t nel, size_t width, int (*comp)(const void *, const void *)) { size_t wgap, i, j, k; char tmp; if ((nel > 1) && (width > 0)) { assert(nel <= ((size_t)(-1)) / width); /* check for overflow */ wgap = 0; do { wgap = 3 * wgap + 1; } while (wgap < (nel-1)/3); /* From the above, we know that either wgap == 1 < nel or */ /* ((wgap-1)/3 < (int) ((nel-1)/3) <= (nel-1)/3 ==> wgap < nel. */ wgap *= width; /* So this can not overflow if wnel doesn't. */ nel *= width; /* Convert nel to 'wnel' */ do { i = wgap; do { j = i; do { register char *a; register char *b; j -= wgap; a = j + ((char *)base); b = a + wgap; if ((*comp)(a, b) <= 0) { break; } k = width; do { tmp = *a; *a++ = *b; *b++ = tmp; } while (--k); } while (j >= wgap); i += width; } while (i < nel); wgap = (wgap - width)/3; } while (wgap); } }