Format fpu64 trimmed

lib_standard_app/format.c

@@ -129,6 +129,24 @@ bool format_fpu64(char *dst, size_t dst_len, const uint64_t value, uint8_t decim
     return true;
 }
 
+bool format_fpu64_trimmed(char *dst, size_t dst_len, const uint64_t value, uint8_t decimals) {
+    if (!format_fpu64(dst, dst_len, value, decimals)) {
+        return false;
+    }
+
+    size_t len = strlen(dst);
+
+    while (len > 0 && (dst[len - 1] == '0' || dst[len - 1] == '.')) {
+        if (dst[len - 1] == '.') {
+            dst[len - 1] = '\0';
+            return true;
+        }
+        len--;
+    }
+    dst[len] = '\0';
+    return true;
+}
+
 int format_hex(const uint8_t *in, size_t in_len, char *out, size_t out_len) {
     if (out_len < 2 * in_len + 1) {
         return -1;

lib_standard_app/format.h

@@ -51,6 +51,23 @@ bool format_u64(char *dst, size_t dst_len, uint64_t value);
  */
 bool format_fpu64(char *dst, size_t dst_len, const uint64_t value, uint8_t decimals);
 
+/**
+ * Format 64-bit unsigned integer as string with decimals and trimmed zeros and dot.
+ *
+ * @param[out] dst
+ *   Pointer to output string.
+ * @param[in]  dst_len
+ *   Length of output string.
+ * @param[in]  value
+ *   64-bit unsigned integer to format.
+ * @param[in]  decimals
+ *   Number of digits after decimal separator.
+ *
+ * @return true if success, false otherwise.
+ *
+ */
+bool format_fpu64_trimmed(char *dst, size_t dst_len, const uint64_t value, uint8_t decimals);
+
 /**
  * Format byte buffer to uppercase hexadecimal string.
  *

unit-tests/lib_standard_app/test_format.c

@@ -82,6 +82,32 @@ static void test_format_fpu64(void **state) {
     assert_false(format_fpu64(temp2, sizeof(temp2) - 20, amount, 18));
 }
 
+static void test_format_fpu64_trimmed(void **state) {
+    (void) state;
+
+    char temp[22] = {0};
+
+    uint64_t amount = 100000000ull;  // satoshi
+    memset(temp, 0, sizeof(temp));
+    assert_true(format_fpu64_trimmed(temp, sizeof(temp), amount, 8));
+    assert_string_equal(temp, "1");  // BTC
+
+    amount = 24964823ull;  // satoshi
+    memset(temp, 0, sizeof(temp));
+    assert_true(format_fpu64_trimmed(temp, sizeof(temp), amount, 8));
+    assert_string_equal(temp, "0.24964823");  // BTC
+
+    amount = 100ull;  // satoshi
+    memset(temp, 0, sizeof(temp));
+    assert_true(format_fpu64_trimmed(temp, sizeof(temp), amount, 8));
+    assert_string_equal(temp, "0.000001");  // BTC
+
+    amount = 1000000000ull;  // satoshi
+    memset(temp, 0, sizeof(temp));
+    assert_true(format_fpu64_trimmed(temp, sizeof(temp), amount, 8));
+    assert_string_equal(temp, "10");  // BTC
+}
+
 static void test_format_hex(void **state) {
     (void) state;
 
@@ -99,6 +125,7 @@ int main() {
     const struct CMUnitTest tests[] = {cmocka_unit_test(test_format_i64),
                                        cmocka_unit_test(test_format_u64),
                                        cmocka_unit_test(test_format_fpu64),
+                                       cmocka_unit_test(test_format_fpu64_trimmed),
                                        cmocka_unit_test(test_format_hex)};
 
     return cmocka_run_group_tests(tests, NULL, NULL);