fix(printf): fix broken right-padding in _ftoa

Fixes #24

printf.c

@@ -262,6 +262,8 @@ static size_t _ntoa_long_long(out_fct_type out, char* buffer, size_t idx, size_t
 #if defined(PRINTF_SUPPORT_FLOAT)
 static size_t _ftoa(out_fct_type out, char* buffer, size_t idx, size_t maxlen, double value, unsigned int prec, unsigned int width, unsigned int flags)
 {
+  const size_t start_idx = idx;
+
   char buf[PRINTF_FTOA_BUFFER_SIZE];
   size_t len  = 0U;
   double diff = 0.0;
@@ -388,7 +390,7 @@ static size_t _ftoa(out_fct_type out, char* buffer, size_t idx, size_t maxlen, d
 
   // append pad spaces up to given width
   if (flags & FLAGS_LEFT) {
-    while (idx < width) {
+    while (idx - start_idx < width) {
       out(' ', buffer, idx++, maxlen);
     }
   }

test/test_suite.cpp

@@ -990,6 +990,12 @@ TEST_CASE("float", "[]" ) {
   test::sprintf(buffer, "%.1f", 3.49);
   REQUIRE(!strcmp(buffer, "3.5"));
 
+  test::sprintf(buffer, "a%-5.1f", 0.5);
+  REQUIRE(!strcmp(buffer, "a0.5  "));
+
+  test::sprintf(buffer, "a%-5.1fend", 0.5);
+  REQUIRE(!strcmp(buffer, "a0.5  end"));
+
   // out of range in the moment, need to be fixed by someone
   test::sprintf(buffer, "%.1f", 1E20);
   REQUIRE(!strcmp(buffer, ""));