summaryrefslogtreecommitdiff
path: root/src/malloc/calloc.c
diff options
context:
space:
mode:
Diffstat (limited to 'src/malloc/calloc.c')
-rw-r--r--src/malloc/calloc.c37
1 files changed, 37 insertions, 0 deletions
diff --git a/src/malloc/calloc.c b/src/malloc/calloc.c
new file mode 100644
index 00000000..322193ca
--- /dev/null
+++ b/src/malloc/calloc.c
@@ -0,0 +1,37 @@
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <errno.h>
+
+static size_t mal0_clear(char *p, size_t n)
+{
+ const size_t pagesz = 4096; /* arbitrary */
+ if (n < pagesz) return n;
+#ifdef __GNUC__
+ typedef uint64_t __attribute__((__may_alias__)) T;
+#else
+ typedef unsigned char T;
+#endif
+ char *pp = p + n;
+ size_t i = (uintptr_t)pp & (pagesz - 1);
+ for (;;) {
+ pp = memset(pp - i, 0, i);
+ if (pp - p < pagesz) return pp - p;
+ for (i = pagesz; i; i -= 2*sizeof(T), pp -= 2*sizeof(T))
+ if (((T *)pp)[-1] | ((T *)pp)[-2])
+ break;
+ }
+}
+
+void *calloc(size_t m, size_t n)
+{
+ if (n && m > (size_t)-1/n) {
+ errno = ENOMEM;
+ return 0;
+ }
+ n *= m;
+ void *p = malloc(n);
+ if (!p) return p;
+ n = mal0_clear(p, n);
+ return memset(p, 0, n);
+}