From 885f5974cdf65b59415837ae97f5a14ef1350670 Mon Sep 17 00:00:00 2001
From: Kacper <kacper@mail.openlinux.dev>
Date: Tue, 9 Dec 2025 19:20:15 +0100
Subject: feat: add gzip and new headers

---
 lib/libm/__expo2f.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 lib/libm/__expo2f.c

(limited to 'lib/libm/__expo2f.c')

diff --git a/lib/libm/__expo2f.c b/lib/libm/__expo2f.c
new file mode 100644
index 00000000..524be700
--- /dev/null
+++ b/lib/libm/__expo2f.c
@@ -0,0 +1,20 @@
+#include "libm.h"
+
+/* k is such that k*ln2 has minimal relative error and x - kln2 > log(FLT_MIN)
+ */
+static const int k = 235;
+static const float kln2 = 0x1.45c778p+7f;
+
+/* expf(x)/2 for x >= log(FLT_MAX), slightly better than
+ * 0.5f*expf(x/2)*expf(x/2) */
+float __expo2f(float x, float sign)
+{
+	float scale;
+
+	/* note that k is odd and scale*scale overflows */
+	SET_FLOAT_WORD(scale, (uint32_t)(0x7f + k / 2) << 23);
+	/* exp(x - k ln2) * 2**(k-1) */
+	/* in directed rounding correct sign before rounding or overflow is
+	 * important */
+	return expf(x - kln2) * (sign * scale) * scale;
+}
-- 
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