1 files changed, 33 insertions, 0 deletions
diff --git a/src/runtime/c/gu/bits.c b/src/runtime/c/gu/bits.c
index 8c43b8477..b5696a19c 100644
--- a/src/runtime/c/gu/bits.c
+++ b/src/runtime/c/gu/bits.c
@@ -41,3 +41,36 @@ gu_decode_double(uint64_t u)
 	}
 	return sign ? copysign(ret, -1.0) : ret;
 }
+
+GU_INTERNAL uint64_t
+gu_encode_double(double d)
+{
+	int sign = signbit(d) > 0;
+	unsigned rawexp;
+	uint64_t mantissa;
+
+	switch (fpclassify(d)) {
+	case FP_NAN:
+		rawexp   = 0x7ff;
+		mantissa = 1;
+		break;
+	case FP_INFINITE:
+		rawexp   = 0x7ff;
+		mantissa = 0;
+		break;
+	default: {
+		int exp;
+		mantissa = (uint64_t) scalbn(frexp(d, &exp), 53);
+		mantissa &= ~ (1ULL << 52);
+		exp -= 53;
+
+		rawexp = exp + 1075;
+	}
+	}
+
+    uint64_t u = (((uint64_t) sign) << 63) |
+                 (((uint64_t) rawexp & 0x7ff) << 52) |
+                 mantissa;
+
+	return u;
+}