From 22421abaf8e6c2cf7609866f04eb005a8ba58fbc Mon Sep 17 00:00:00 2001
From: Viviane Potocnik <vivianep@iis.ee.ethz.ch>
Date: Fri, 20 Oct 2023 21:45:54 +0200
Subject: [PATCH] math: add ceil function

---
 sw/math/src/math/ceil.c  | 31 +++++++++++++++++++++++++++++++
 sw/math/src/math/ceilf.c | 27 +++++++++++++++++++++++++++
 sw/math/src/math/ceill.c | 34 ++++++++++++++++++++++++++++++++++
 3 files changed, 92 insertions(+)
 create mode 100644 sw/math/src/math/ceil.c
 create mode 100644 sw/math/src/math/ceilf.c
 create mode 100644 sw/math/src/math/ceill.c

diff --git a/sw/math/src/math/ceil.c b/sw/math/src/math/ceil.c
new file mode 100644
index 000000000..b13e6f2d6
--- /dev/null
+++ b/sw/math/src/math/ceil.c
@@ -0,0 +1,31 @@
+#include "libm.h"
+
+#if FLT_EVAL_METHOD==0 || FLT_EVAL_METHOD==1
+#define EPS DBL_EPSILON
+#elif FLT_EVAL_METHOD==2
+#define EPS LDBL_EPSILON
+#endif
+static const double_t toint = 1/EPS;
+
+double ceil(double x)
+{
+	union {double f; uint64_t i;} u = {x};
+	int e = u.i >> 52 & 0x7ff;
+	double_t y;
+
+	if (e >= 0x3ff+52 || x == 0)
+		return x;
+	/* y = int(x) - x, where int(x) is an integer neighbor of x */
+	if (u.i >> 63)
+		y = x - toint + toint - x;
+	else
+		y = x + toint - toint - x;
+	/* special case because of non-nearest rounding modes */
+	if (e <= 0x3ff-1) {
+		FORCE_EVAL(y);
+		return u.i >> 63 ? -0.0 : 1;
+	}
+	if (y < 0)
+		return x + y + 1;
+	return x + y;
+}
diff --git a/sw/math/src/math/ceilf.c b/sw/math/src/math/ceilf.c
new file mode 100644
index 000000000..869835f39
--- /dev/null
+++ b/sw/math/src/math/ceilf.c
@@ -0,0 +1,27 @@
+#include "libm.h"
+
+float ceilf(float x)
+{
+	union {float f; uint32_t i;} u = {x};
+	int e = (int)(u.i >> 23 & 0xff) - 0x7f;
+	uint32_t m;
+
+	if (e >= 23)
+		return x;
+	if (e >= 0) {
+		m = 0x007fffff >> e;
+		if ((u.i & m) == 0)
+			return x;
+		FORCE_EVAL(x + 0x1p120f);
+		if (u.i >> 31 == 0)
+			u.i += m;
+		u.i &= ~m;
+	} else {
+		FORCE_EVAL(x + 0x1p120f);
+		if (u.i >> 31)
+			u.f = -0.0;
+		else if (u.i << 1)
+			u.f = 1.0;
+	}
+	return u.f;
+}
diff --git a/sw/math/src/math/ceill.c b/sw/math/src/math/ceill.c
new file mode 100644
index 000000000..60a83020d
--- /dev/null
+++ b/sw/math/src/math/ceill.c
@@ -0,0 +1,34 @@
+#include "libm.h"
+
+#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
+long double ceill(long double x)
+{
+	return ceil(x);
+}
+#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
+
+static const long double toint = 1/LDBL_EPSILON;
+
+long double ceill(long double x)
+{
+	union ldshape u = {x};
+	int e = u.i.se & 0x7fff;
+	long double y;
+
+	if (e >= 0x3fff+LDBL_MANT_DIG-1 || x == 0)
+		return x;
+	/* y = int(x) - x, where int(x) is an integer neighbor of x */
+	if (u.i.se >> 15)
+		y = x - toint + toint - x;
+	else
+		y = x + toint - toint - x;
+	/* special case because of non-nearest rounding modes */
+	if (e <= 0x3fff-1) {
+		FORCE_EVAL(y);
+		return u.i.se >> 15 ? -0.0 : 1;
+	}
+	if (y < 0)
+		return x + y + 1;
+	return x + y;
+}
+#endif