From ee1dfffae5ad694bb0fb687bbc4752c15874ea06 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Florian=20M=C3=A4rkl?= <info@florianmaerkl.de>
Date: Thu, 11 Mar 2021 20:55:47 +0100
Subject: [PATCH] Add rz_num_align_delta()

---
 librz/include/rz_util/rz_num.h | 15 +++++++++++++++
 test/unit/test_unum.c          | 15 +++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/librz/include/rz_util/rz_num.h b/librz/include/rz_util/rz_num.h
index 0b7263acdf..f29d947dba 100644
--- a/librz/include/rz_util/rz_num.h
+++ b/librz/include/rz_util/rz_num.h
@@ -103,6 +103,21 @@ static inline st64 rz_num_abs(st64 num) {
 	return num < 0 ? -num : num;
 }
 
+/**
+ * \brief Padding to align v to the next alignment-boundary.
+ * \return the least `d` such that `(v + d) % alignment == 0`.
+ */
+static inline ut64 rz_num_align_delta(ut64 v, ut64 alignment) {
+	if (!alignment) {
+		return 0;
+	}
+	ut64 excess = v % alignment;
+	if (!excess) {
+		return 0;
+	}
+	return alignment - excess;
+}
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/test/unit/test_unum.c b/test/unit/test_unum.c
index 76de2da026..bde2f2261c 100644
--- a/test/unit/test_unum.c
+++ b/test/unit/test_unum.c
@@ -129,6 +129,20 @@ bool test_rz_num_str_split_list() {
 	mu_end;
 }
 
+bool test_rz_num_align_delta() {
+	ut64 d = rz_num_align_delta(0, 8);
+	mu_assert_eq(d, 0, "align delta");
+	d = rz_num_align_delta(3, 8);
+	mu_assert_eq(d, 5, "align delta");
+	d = rz_num_align_delta(0x10, 8);
+	mu_assert_eq(d, 0, "align delta");
+	d = rz_num_align_delta(0x11, 8);
+	mu_assert_eq(d, 7, "align delta");
+	d = rz_num_align_delta(0x42, 0);
+	mu_assert_eq(d, 0, "align delta");
+	mu_end;
+}
+
 bool all_tests() {
 	mu_run_test(test_rz_num_units);
 	mu_run_test(test_rz_num_minmax_swap_i);
@@ -137,6 +151,7 @@ bool all_tests() {
 	mu_run_test(test_rz_num_str_len);
 	mu_run_test(test_rz_num_str_split);
 	mu_run_test(test_rz_num_str_split_list);
+	mu_run_test(test_rz_num_align_delta);
 	return tests_passed != tests_run;
 }