[babl] add internal babl_parse_double; to avoid using atof

[Øyvind Kolås <ok src gnome org>]

commit 413e7f19546f9730930e69b0bb3cc07651cb0a59
Author: Øyvind Kolås <pippin gimp org>
Date:   Mon Jun 9 02:30:38 2014 +0200

    add internal babl_parse_double; to avoid using atof
    
    atof is locale dependent; it was being used two places parsing floating point
    values from environment variables.

 babl/babl-fish-path.c  |    2 +-
 babl/babl-fish-stats.c |    2 +-
 babl/babl-internal.h   |   22 ++++++++++++++++++++++
 3 files changed, 24 insertions(+), 2 deletions(-)
---
diff --git a/babl/babl-fish-path.c b/babl/babl-fish-path.c
index 3b90edf..5dc0601 100644
--- a/babl/babl-fish-path.c
+++ b/babl/babl-fish-path.c
@@ -109,7 +109,7 @@ static double legal_error (void)
 
   env = getenv ("BABL_TOLERANCE");
   if (env && env[0] != '\0')
-    error = atof (env);
+    error = babl_parse_double (env);
   else
     error = BABL_LEGAL_ERROR;
   return error;
diff --git a/babl/babl-fish-stats.c b/babl/babl-fish-stats.c
index 9c6d52e..c0b34de 100644
--- a/babl/babl-fish-stats.c
+++ b/babl/babl-fish-stats.c
@@ -252,7 +252,7 @@ static double legal_error (void)
 
   env = getenv ("BABL_TOLERANCE");
   if (env && env[0] != '\0')
-    error = atof (env);
+    error = babl_parse_double (env);
   else
     error = BABL_LEGAL_ERROR;
   return error;
diff --git a/babl/babl-internal.h b/babl/babl-internal.h
index cc05660..eb80dd0 100644
--- a/babl/babl-internal.h
+++ b/babl/babl-internal.h
@@ -295,4 +295,26 @@ babl_##klass##_from_id (int id)                               \
 
 #define BABL(obj)  ((Babl*)(obj))
 
+static inline double babl_parse_double (const char *str)
+{
+  double result = 0;
+  if (!str)
+    return 0.0;
+  result = atoi (str);
+  if (strchr (str, '.'))
+  {
+    char *p = strchr (str, '.') + 1;
+    double d = 10;
+    for (;*p && *p > '0' && *p < '9';p++, d *= 10)
+    {
+      if (result >= 0)
+        result += (*p - '0') / d;
+      else
+        result -= (*p - '0') / d;
+    }
+  }
+  return result;
+}
+
+
 #endif