[Feature] Import fpconv library

Source: https://github.com/night-shift/fpconv

1 files changed, 33 insertions, 0 deletions

diff --git a/contrib/fpconv/fpconv.h b/contrib/fpconv/fpconv.h
new file mode 100644
index 000000000..58bbcccbb
--- /dev/null
+++ b/contrib/fpconv/fpconv.h
@@ -0,0 +1,33 @@
+#ifndef FPCONV_H
+#define FPCONV_H
+
+/* Fast and accurate double to string conversion based on Florian Loitsch's
+ * Grisu-algorithm[1].
+ *
+ * Input:
+ * fp -> the double to convert, dest -> destination buffer.
+ * The generated string will never be longer than 24 characters.
+ * Make sure to pass a pointer to at least 24 bytes of memory.
+ * The emitted string will not be null terminated.
+ *
+ * Output:
+ * The number of written characters.
+ *
+ * Exemplary usage:
+ *
+ * void print(double d)
+ * {
+ *      char buf[24 + 1] // plus null terminator
+ *      int str_len = fpconv_dtoa(d, buf);
+ *
+ *      buf[str_len] = '\0';
+ *      printf("%s", buf);
+ * }
+ *
+ */
+
+int fpconv_dtoa(double fp, char dest[24]);
+
+#endif
+
+/* [1] http://florian.loitsch.com/publications/dtoa-pldi2010.pdf */