From d06225647ebf64f2445391ee7c73e19ba216f3eb Mon Sep 17 00:00:00 2001
From: Kray-G <nagai.kazuya@gmail.com>
Date: Mon, 11 Nov 2019 12:46:50 +0900
Subject: [PATCH 1/2] issue #17: added qsort() in stdlib.

---
 kccrt/libsrc/stdlib.c | 38 ++++++++++++++++++++++++++++++++++++++
 samples/qsort.c       | 18 ++++++++++++++++++
 2 files changed, 56 insertions(+)
 create mode 100644 samples/qsort.c

diff --git a/kccrt/libsrc/stdlib.c b/kccrt/libsrc/stdlib.c
index c8d23f8..f1efc84 100644
--- a/kccrt/libsrc/stdlib.c
+++ b/kccrt/libsrc/stdlib.c
@@ -18,4 +18,42 @@ int rand(void)
     return (unsigned)(__kcc_rand_seed / 65536L) % (RAND_MAX+1);
 }
 
+#define SWAP(x, y, size)            \
+    do {                            \
+        size_t s = (size);          \
+        char *a = (x), *b = (y);    \
+        do {                        \
+            char t = *a;            \
+            *a++ = *b;              \
+            *b++ = t;               \
+        } while (--s > 0);          \
+    } while (0)                     \
+    /**/
+
+#define KCCQ(a, i)    ((char *)a + (i) * size)
+
+void __quicksort(int first, int last, void *base, size_t size, int (*comp)(const void *, const void *))
+{
+    int i, j;
+    void *x = KCCQ(base, (first + last) / 2);
+    i = first;  j = last;
+    for ( ; ; ) {
+        while (comp(x, KCCQ(base, i)) > 0) i++;
+        while (comp(KCCQ(base, j), x) > 0) j--;
+        if (i >= j) break;
+        SWAP(KCCQ(base,i), KCCQ(base,j), size);
+        i++;
+        j--;
+    }
+    if (first  < i - 1) __quicksort(first , i - 1, base, size, comp);
+    if (j + 1 < last) __quicksort(j + 1, last, base, size, comp);
+}
+
+#undef KCCQ
+
+void qsort(void *base, size_t n, size_t size, int (*comp)(const void *, const void *))
+{
+    __quicksort(0, n - 1, base, size, comp);
+}
+
 #endif
diff --git a/samples/qsort.c b/samples/qsort.c
new file mode 100644
index 0000000..98e210c
--- /dev/null
+++ b/samples/qsort.c
@@ -0,0 +1,18 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+int cmp(const void *p, const void *q)
+{
+    return *(int*)p - *(int*)q;
+}
+
+main()
+{
+    int values[] = { 49, 2, 180, 23, 77, 13, 29, 88 };
+    int n, i;
+
+    n = sizeof(values)/sizeof(int);
+    qsort(values, n, sizeof(int), cmp);
+    for (i = 0; i < n; i++)
+        printf("values[%d] = %d\n", i, values[i]);
+}

From bf0fe554e8bb0ed7b16af6b844ba8e25a291c4c3 Mon Sep 17 00:00:00 2001
From: Kray-G <nagai.kazuya@gmail.com>
Date: Mon, 11 Nov 2019 14:29:39 +0900
Subject: [PATCH 2/2] issue #17: updated sample for qsort.

---
 samples/qsort.c | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/samples/qsort.c b/samples/qsort.c
index 98e210c..cabf020 100644
--- a/samples/qsort.c
+++ b/samples/qsort.c
@@ -6,13 +6,22 @@ int cmp(const void *p, const void *q)
     return *(int*)p - *(int*)q;
 }
 
-main()
+#define N 20
+int a[N];
+
+int main(void)
 {
-    int values[] = { 49, 2, 180, 23, 77, 13, 29, 88 };
-    int n, i;
+    int i;
 
-    n = sizeof(values)/sizeof(int);
-    qsort(values, n, sizeof(int), cmp);
-    for (i = 0; i < n; i++)
-        printf("values[%d] = %d\n", i, values[i]);
+    printf("Before:");
+    for (i = 0; i < N; i++) {
+        a[i] = rand() / (RAND_MAX / 100 + 1);
+        printf(" %2d", a[i]);
+    }
+    printf("\n");
+    qsort(a, sizeof(a)/sizeof(a[0]), sizeof(a[0]), cmp);
+    printf("After: ");
+    for (i = 0; i < N; i++) printf(" %2d", a[i]);
+    printf("\n");
+    return 0;
 }