Add experimental support for long double. Fixes issue #194

1 files changed, 59 insertions, 0 deletions

diff --git a/ext/ffi_c/LongDouble.c b/ext/ffi_c/LongDouble.c
new file mode 100644
index 0000000..ae394c8
--- /dev/null
+++ b/ext/ffi_c/LongDouble.c
@@ -0,0 +1,59 @@
+#include "LongDouble.h"
+#include <stdio.h>
+#include <stdarg.h>
+#include <float.h>
+
+static VALUE rb_cBigDecimal = Qnil;
+static VALUE bigdecimal_load(VALUE unused);
+static VALUE bigdecimal_failed(VALUE value);
+
+VALUE 
+rbffi_longdouble_new(long double ld)
+{
+    if (!RTEST(rb_cBigDecimal)) {
+        /* allow fallback if the bigdecimal library is unavailable in future ruby versions */
+        rb_cBigDecimal = rb_rescue(bigdecimal_load, Qnil, bigdecimal_failed, rb_cObject);
+    }
+
+    if (RTEST(rb_cBigDecimal) && rb_cBigDecimal != rb_cObject) {
+        char buf[128];
+        return rb_funcall(rb_cBigDecimal, rb_intern("new"), 1, rb_str_new(buf, sprintf(buf, "%.35Le", ld)));
+    }
+
+    /* Fall through to handling as a float */
+    return rb_float_new(ld);
+}
+
+long double 
+rbffi_num2longdouble(VALUE value)
+{
+    if (TYPE(value) == T_FLOAT) {
+        return rb_num2dbl(value);
+    }
+    
+    if (!RTEST(rb_cBigDecimal) && rb_const_defined(rb_cObject, rb_intern("BigDecimal"))) {
+        rb_cBigDecimal = rb_const_get(rb_cObject, rb_intern("BigDecimal"));
+    }
+
+    if (RTEST(rb_cBigDecimal) && rb_cBigDecimal != rb_cObject && RTEST(rb_obj_is_kind_of(value, rb_cBigDecimal))) {
+        VALUE s = rb_funcall(value, rb_intern("to_s"), 1, rb_str_new2("E"));
+        return strtold(RSTRING_PTR(s), NULL);
+    }
+
+    /* Fall through to handling as a float */
+    return rb_num2dbl(value);
+}
+
+
+static VALUE 
+bigdecimal_load(VALUE unused)
+{
+    rb_require("bigdecimal");
+    return rb_const_get(rb_cObject, rb_intern("BigDecimal"));
+}
+
+static VALUE 
+bigdecimal_failed(VALUE value)
+{
+    return value;
+}