utility functions to reverse and wrap arrays.

source/blender/blenlib/BLI_array.h

@@ -173,4 +173,14 @@ void _bli_array_grow_func(void **arr_p, const void *arr_static,
 		MEM_freeN(arr);                                                       \
 	} (void)0
 
+
+void _bli_array_reverse(void *arr, unsigned int arr_len, size_t arr_stride);
+#define BLI_array_reverse(arr, arr_len) \
+	_bli_array_reverse(arr, arr_len, sizeof(*(arr)))
+
+void _bli_array_wrap(void *arr, unsigned int arr_len, size_t arr_stride, int dir);
+#define BLI_array_wrap(arr, arr_len, dir) \
+	_bli_array_wrap(arr, arr_len, sizeof(*(arr)), dir)
+
+
 #endif  /* __BLI_ARRAY_H__ */

source/blender/blenlib/intern/BLI_array.c

@@ -59,9 +59,14 @@
  */
 
 #include <string.h>
+#include <stdlib.h>
 
 #include "BLI_array.h"
 
+#include "BLI_sys_types.h"
+#include "BLI_utildefines.h"
+#include "BLI_alloca.h"
+
 #include "MEM_guardedalloc.h"
 
 /**
@@ -95,3 +100,40 @@ void _bli_array_grow_func(void **arr_p, const void *arr_static,
 	arr_count += num;
 #endif
 }
+
+void _bli_array_reverse(void *arr_v, unsigned int arr_len, size_t arr_stride)
+{
+	const unsigned int arr_half_stride = (arr_len / 2) * arr_stride;
+	unsigned int i, i_end;
+	char *arr = arr_v;
+	char *buf = BLI_array_alloca(buf, arr_stride);
+
+	for (i = 0, i_end = (arr_len - 1) * arr_stride;
+	     i < arr_half_stride;
+	     i += arr_stride, i_end -= arr_stride)
+	{
+		memcpy(buf, &arr[i], arr_stride);
+		memcpy(&arr[i], &arr[i_end], arr_stride);
+		memcpy(&arr[i_end], buf, arr_stride);
+	}
+}
+
+void _bli_array_wrap(void *arr_v, unsigned int arr_len, size_t arr_stride, int dir)
+{
+	char *arr = arr_v;
+	char *buf = BLI_array_alloca(buf, arr_stride);
+
+	if (dir == -1) {
+		memcpy(buf, arr, arr_stride);
+		memmove(arr, arr + arr_stride, arr_stride * (arr_len - 1));
+		memcpy(arr + (arr_stride * (arr_len - 1)), buf, arr_stride);
+	}
+	else if (dir == 1) {
+		memcpy(buf, arr + (arr_stride * (arr_len - 1)), arr_stride);
+		memmove(arr + arr_stride, arr, arr_stride * (arr_len - 1));
+		memcpy(arr, buf, arr_stride);
+	}
+	else {
+		BLI_assert(0);
+	}
+}