util/cse*: Add cse_helpers.{c,h}

This change moves `read_member` and `write_member` helper functions
out of cse_fpt.c and cse_serger.c into cse_helpers.c to avoid
duplication.

BUG=b:189177186,b:189167923

Change-Id: I7b646b29c9058d892bb0fc9824ef1b4340d2510c
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/58201
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>

util/cbfstool/cse_helpers.c

@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Helper functions for cse_serger and cse_fpt */
+
+#include <commonlib/endian.h>
+
+#include "cse_helpers.h"
+
+void write_member(struct buffer *buff, void *src, size_t size)
+{
+	void *dst = buffer_get(buff);
+
+	switch (size) {
+	case 1:
+		write_le8(dst, *(uint8_t *)src);
+		break;
+	case 2:
+		write_le16(dst, *(uint16_t *)src);
+		break;
+	case 4:
+		write_le32(dst, *(uint32_t *)src);
+		break;
+	case 8:
+		write_le64(dst, *(uint64_t *)src);
+		break;
+	default:
+		memcpy(dst, src, size);
+		break;
+	}
+
+	buffer_seek(buff, size);
+}
+
+void read_member(struct buffer *buff, void *dst, size_t size)
+{
+	const void *src = buffer_get(buff);
+
+	switch (size) {
+	case 1:
+		*(uint8_t *)dst = read_le8(src);
+		break;
+	case 2:
+		*(uint16_t *)dst = read_le16(src);
+		break;
+	case 4:
+		*(uint32_t *)dst = read_le32(src);
+		break;
+	case 8:
+		*(uint64_t *)dst = read_le64(src);
+		break;
+	default:
+		memcpy(dst, src, size);
+		break;
+	}
+
+	buffer_seek(buff, size);
+}