Add build system scaffolding and libc headers

1 files changed, 243 insertions, 0 deletions

diff --git a/lib/libc/stdlib/qsort_r.c b/lib/libc/stdlib/qsort_r.c
new file mode 100644
index 00000000..2fc39a6f
--- /dev/null
+++ b/lib/libc/stdlib/qsort_r.c
@@ -0,0 +1,243 @@
+/* Copyright (C) 2011 by Lynn Ochs
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+/* Minor changes by Rich Felker for integration in musl, 2011-04-27. */
+
+/* Smoothsort, an adaptive variant of Heapsort.  Memory usage: O(1).
+   Run time: Worst case O(n log n), close to O(n) in the mostly-sorted case. */
+
+#define _BSD_SOURCE
+#include <stdlib.h>
+#include <string.h>
+
+#define ntz(x) __builtin_ctzl((x))
+
+typedef int (*cmpfun)(const void *, const void *, void *);
+
+static inline int pntz(size_t p[2])
+{
+	int r = ntz(p[0] - 1);
+	if (r != 0 ||
+	    (r = 8 * sizeof(size_t) + ntz(p[1])) != 8 * sizeof(size_t)) {
+		return r;
+	}
+	return 0;
+}
+
+static void cycle(size_t width, unsigned char *ar[], int n)
+{
+	unsigned char tmp[256];
+	size_t l;
+	int i;
+
+	if (n < 2) {
+		return;
+	}
+
+	ar[n] = tmp;
+	while (width) {
+		l = sizeof(tmp) < width ? sizeof(tmp) : width;
+		memcpy(ar[n], ar[0], l);
+		for (i = 0; i < n; i++) {
+			memcpy(ar[i], ar[i + 1], l);
+			ar[i] += l;
+		}
+		width -= l;
+	}
+	ar[n] = NULL;
+}
+
+/* shl() and shr() need n > 0 */
+static inline void shl(size_t p[2], int n)
+{
+	if (n >= 8 * sizeof(size_t)) {
+		n -= 8 * sizeof(size_t);
+		p[1] = p[0];
+		p[0] = 0;
+	}
+	p[1] <<= n;
+	p[1] |= (n < sizeof(size_t) * 8) ? p[0] >> (sizeof(size_t) * 8 - n) : 0;
+	p[0] <<= n;
+}
+
+static inline void shr(size_t p[2], int n)
+{
+	size_t bits = sizeof(size_t) * 8;
+
+	if (n >= 8 * sizeof(size_t)) {
+		n -= 8 * sizeof(size_t);
+		p[0] = p[1];
+		p[1] = 0;
+	}
+
+	p[0] >>= n;
+	p[0] |= (n > 0 && n < bits) ? p[1] << (bits - n) : 0;
+	p[1] >>= n;
+}
+
+static void sift(unsigned char *head, size_t width, cmpfun cmp, void *arg,
+		 int pshift, size_t lp[])
+{
+	unsigned char *rt, *lf;
+	unsigned char *ar[14 * sizeof(size_t) + 1];
+	int i = 1;
+
+	ar[0] = head;
+	while (pshift > 1) {
+		rt = head - width;
+		lf = head - width - lp[pshift - 2];
+
+		if (cmp(ar[0], lf, arg) >= 0 && cmp(ar[0], rt, arg) >= 0) {
+			break;
+		}
+		if (cmp(lf, rt, arg) >= 0) {
+			ar[i++] = lf;
+			head = lf;
+			pshift -= 1;
+		} else {
+			ar[i++] = rt;
+			head = rt;
+			pshift -= 2;
+		}
+	}
+	cycle(width, ar, i);
+}
+
+static void trinkle(unsigned char *head, size_t width, cmpfun cmp, void *arg,
+		    size_t pp[2], int pshift, int trusty, size_t lp[],
+		    int max_lp_index)
+{
+	unsigned char *stepson, *rt, *lf;
+	size_t p[2];
+	unsigned char *ar[14 * sizeof(size_t) + 1];
+	int i = 1;
+	int trail;
+
+	p[0] = pp[0];
+	p[1] = pp[1];
+
+	ar[0] = head;
+	while (p[0] != 1 || p[1] != 0) {
+		if (pshift < 0 || pshift > max_lp_index || pshift >= 64)
+			break;
+
+		stepson = head - lp[pshift];
+		if (cmp(stepson, ar[0], arg) <= 0) {
+			break;
+		}
+		if (!trusty && pshift > 1 && pshift - 2 >= 0 &&
+		    pshift - 2 <= max_lp_index) {
+			rt = head - width;
+			lf = head - width - lp[pshift - 2];
+			if (cmp(rt, stepson, arg) >= 0 ||
+			    cmp(lf, stepson, arg) >= 0) {
+				break;
+			}
+		}
+
+		ar[i++] = stepson;
+		head = stepson;
+		trail = pntz(p);
+		shr(p, trail);
+		pshift += trail;
+		trusty = 0;
+	}
+	if (!trusty) {
+		cycle(width, ar, i);
+		sift(head, width, cmp, arg, pshift, lp);
+	}
+}
+
+void qsort_r(void *base, size_t nel, size_t width, cmpfun cmp, void *arg)
+{
+	size_t lp[64];
+	size_t i, size = width * nel;
+	unsigned char *head, *high;
+	size_t p[2] = { 1, 0 };
+	int pshift = 1;
+	int trail;
+	int max_lp_index;
+
+	if (!size)
+		return;
+
+	head = base;
+	high = head + size - width;
+
+	/* Precompute Leonardo numbers, scaled by element width */
+	for (lp[0] = lp[1] = width, i = 2;
+	     (lp[i] = lp[i - 2] + lp[i - 1] + width) < size && i < 63; i++)
+		;
+	max_lp_index = i - 1;
+
+	while (head < high) {
+		if ((p[0] & 3) == 3) {
+			sift(head, width, cmp, arg, pshift, lp);
+			shr(p, 2);
+			pshift += 2;
+		} else {
+			if (pshift - 1 >= 0 && pshift - 1 <= max_lp_index &&
+			    lp[pshift - 1] >= high - head) {
+				trinkle(head, width, cmp, arg, p, pshift, 0, lp,
+					max_lp_index);
+			} else {
+				sift(head, width, cmp, arg, pshift, lp);
+			}
+
+			if (pshift == 1) {
+				shl(p, 1);
+				pshift = 0;
+			} else {
+				shl(p, pshift - 1);
+				pshift = 1;
+			}
+		}
+
+		p[0] |= 1;
+		head += width;
+	}
+
+	trinkle(head, width, cmp, arg, p, pshift, 0, lp, max_lp_index);
+
+	while (pshift != 1 || p[0] != 1 || p[1] != 0) {
+		if (pshift <= 1) {
+			trail = pntz(p);
+			shr(p, trail);
+			pshift += trail;
+		} else {
+			shl(p, 2);
+			pshift -= 2;
+			p[0] ^= 7;
+			shr(p, 1);
+			if (pshift >= 0 && pshift <= max_lp_index &&
+			    pshift < 64) {
+				trinkle(head - lp[pshift] - width, width, cmp,
+					arg, p, pshift + 1, 1, lp,
+					max_lp_index);
+			}
+			shl(p, 1);
+			p[0] |= 1;
+			trinkle(head - width, width, cmp, arg, p, pshift, 1, lp,
+				max_lp_index);
+		}
+		head -= width;
+	}
+}