From c0b2957c6709802ee0b1fc51a1117d919a76e75c Mon Sep 17 00:00:00 2001
From: Lars Mueller <appgurulars@gmx.de>
Date: Wed, 8 Jun 2022 10:16:47 +0200
Subject: [PATCH] Fix binary.write_float

---
 binary.lua | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/binary.lua b/binary.lua
index 25b11a1..9c0d4fe 100644
--- a/binary.lua
+++ b/binary.lua
@@ -104,10 +104,14 @@ function write_float(write_byte, number, on_write, double)
 	end
 	local mantissa, exponent = math_frexp(number)
 	exponent = exponent + 127
+	if number == 0 then exponent = 0 end -- zero must be written as a subnormal number
 	if exponent > 1 then
 		-- TODO ensure this deals properly with subnormal numbers
 		mantissa = mantissa * 2 - 1
 		exponent = exponent - 1
+	elseif exponent < 0 then -- number is currently sub-subnormal, subnormalize
+		mantissa = mantissa * 2^(exponent-1)
+		exponent = 0
 	end
 	local sign_byte = sign + math_floor(exponent / 2)
 	if double == nil then