mem: Add memswap() function

[ccan] / ccan / mem / mem.c

diff --git a/ccan/mem/mem.c b/ccan/mem/mem.c
index 91c9961a52ecd92d1372dae98b07f54902e25f22..5b4b3508090dfb10dc7eea9236eb42ed54b92834 100644 (file)
--- a/ccan/mem/mem.c
+++ b/ccan/mem/mem.c
@@ -2,6 +2,7 @@
 
 #include "config.h"
 
+#include <assert.h>
 #include <string.h>
 #include <ccan/mem/mem.h>
 
@@ -64,3 +65,26 @@ void *memcchr(void const *data, int c, size_t data_len)
 
        return NULL;
 }
+
+#define MEMSWAP_TMP_SIZE       256
+
+void memswap(void *a, void *b, size_t n)
+{
+       char *ap = a;
+       char *bp = b;
+       char tmp[MEMSWAP_TMP_SIZE];
+
+       assert(!memoverlaps(a, n, b, n));
+
+       while (n) {
+               size_t m = n > MEMSWAP_TMP_SIZE ? MEMSWAP_TMP_SIZE : n;
+
+               memcpy(tmp, bp, m);
+               memcpy(bp, ap, m);
+               memcpy(ap, tmp, m);
+
+               ap += m;
+               bp += m;
+               n -= m;
+       }
+}