From b045a37391a2b2e2d674cc6967b16e57538dd786 Mon Sep 17 00:00:00 2001
From: Ryan Flynn <parseerror@gmail.com>
Date: Sat, 3 Nov 2012 22:20:54 -0700
Subject: [PATCH] issue #31: encode floating point numbers with less precision
 if possible. fails a few etap tests, though I believe it's due to the
 specific values expected

---
 c_src/encoder.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/c_src/encoder.c b/c_src/encoder.c
index ce71c1b..00a9dba 100644
--- a/c_src/encoder.c
+++ b/c_src/encoder.c
@@ -4,6 +4,7 @@
 #include <assert.h>
 #include <stdio.h>
 #include <string.h>
+#include <float.h>
 
 #include "erl_nif.h"
 #include "jiffy.h"
@@ -401,7 +402,12 @@ enc_double(Encoder* e, double val)
 
     start = &(e->p[e->i]);
 
-    sprintf(start, "%0.20g", val);
+    // try to encode doubles using the fewest digits possible...
+    if (snprintf(start, 32, "%.*g", DBL_DIG, val) > FLT_DIG)
+    {
+        // ...fall back to full expansion to be safe
+        snprintf(start, 32, "%.*g", LDBL_DIG, val);
+    }
     len = strlen(start);
 
     // Check if we have a decimal point