1 files changed, 51 insertions, 0 deletions
diff --git a/lib/avb/fsl/utils.c b/lib/avb/fsl/utils.c
new file mode 100644
index 0000000000..ec50c70593
--- /dev/null
+++ b/lib/avb/fsl/utils.c
@@ -0,0 +1,51 @@
+
+#include <common.h>
+#include <stdlib.h>
+
+#include "debug.h"
+#include "utils.h"
+
+/* get margin_pos struct from offset [to the partition start/end] and num_bytes to read/write */
+int get_margin_pos(uint64_t part_start, uint64_t part_end, unsigned long blksz,
+				margin_pos_t *margin, int64_t offset, size_t num_bytes, bool allow_partial) {
+	long off;
+	assert(margin != NULL);
+	if (blksz == 0 || part_start > part_end)
+		return -1;
+
+	if (offset < 0) {
+		margin->blk_start = (offset + 1) / blksz + part_end;
+		margin->start = (off = offset % blksz) == 0 ? 0 : blksz + off; // offset == -1 means the last byte?, or start need -1
+		if (offset + num_bytes - 1 >= 0) {
+			if (!allow_partial)
+				return -1;
+			margin->blk_end = part_end;
+			margin->end = blksz - 1;
+		} else {
+			margin->blk_end = (num_bytes + offset) / blksz + part_end; // which blk the last byte is in
+			margin->end = (off = (num_bytes + offset - 1) % blksz) == 0 ?
+					0 : blksz + off; // last byte
+		}
+	} else {
+		margin->blk_start = offset / blksz + part_start;
+		margin->start = offset % blksz;
+		margin->blk_end = (offset + num_bytes - 1) / blksz + part_start ;
+		margin->end = (offset + num_bytes - 1) % blksz;
+		if (margin->blk_end > part_end) {
+			if (!allow_partial)
+				return -1;
+			margin->blk_end = part_end;
+			margin->end = blksz - 1;
+		}
+	}
+	VDEBUG("bs=%ld, be=%ld, s=%ld, e=%ld\n",
+			margin->blk_start, margin->blk_end, margin->start, margin->end);
+
+	if (margin->blk_start > part_end || margin->blk_start < part_start)
+		return -1;
+	long multi = margin->blk_end - margin->blk_start - 1 +
+		    (margin->start == 0) + (margin->end == blksz -1);
+	margin->multi = multi > 0 ? multi : 0;
+	VDEBUG("bm=%ld\n", margin->multi);
+	return 0;
+}