From f36d0573cd0f80b271b9f07a7215fa237d14ae9a Mon Sep 17 00:00:00 2001
From: kineye <27766253+JanikkinaJ@users.noreply.github.com.>
Date: Sat, 7 Feb 2026 16:09:29 +0100
Subject: [PATCH] zig libc: add rint

---
 lib/c/math.zig                      | 57 +++++++++++++++++++++++++++++
 lib/libc/musl/src/math/rint.c       | 28 --------------
 lib/libc/musl/src/math/s390x/rint.c | 15 --------
 src/libs/musl.zig                   |  4 --
 4 files changed, 57 insertions(+), 47 deletions(-)
 delete mode 100644 lib/libc/musl/src/math/rint.c
 delete mode 100644 lib/libc/musl/src/math/s390x/rint.c

diff --git a/lib/c/math.zig b/lib/c/math.zig
index 85b871c695ef5c4233ba9c6375d41f6347605687..2c02597bb2271bd9a83cf6f4cf35b8cd8afdf9fc 100644
--- a/lib/c/math.zig
+++ b/lib/c/math.zig
@@ -56,6 +56,7 @@ comptime {
     if (builtin.target.isMuslLibC()) {
         symbol(&copysignf, "copysignf");
         symbol(&copysign, "copysign");
+        symbol(&rint, "rint");
     }
     symbol(&copysignl, "copysignl");
 }
@@ -158,3 +159,59 @@ fn pow10(x: f64) callconv(.c) f64 {
 fn pow10f(x: f32) callconv(.c) f32 {
     return exp10f(x);
 }
+
+fn rint(x: f64) callconv(.c) f64 {
+    const toint: f64 = 1.0 / @as(f64, std.math.floatEps(f64));
+    const a: u64 = @bitCast(x);
+    const e = a >> 52 & 0x7ff;
+    const s = a >> 63;
+    var y: f64 = undefined;
+
+    if (e >= 0x3ff + 52) {
+        return x;
+    }
+    if (s == 1) {
+        y = x - toint + toint;
+    } else {
+        y = x + toint - toint;
+    }
+    if (y == 0) {
+        return if (s == 1) -0.0 else 0;
+    }
+    return y;
+}
+
+test "rint" {
+    // Positive numbers round correctly
+    try std.testing.expectEqual(@as(f64, 42.0), rint(42.2));
+    try std.testing.expectEqual(@as(f64, 42.0), rint(41.8));
+
+    // Negative numbers round correctly
+    try std.testing.expectEqual(@as(f64, -6.0), rint(-5.9));
+    try std.testing.expectEqual(@as(f64, -6.0), rint(-6.1));
+
+    // No rounding needed test
+    try std.testing.expectEqual(@as(f64, 5.0), rint(5.0));
+    try std.testing.expectEqual(@as(f64, -10.0), rint(-10.0));
+    try std.testing.expectEqual(@as(f64, 0.0), rint(0.0));
+
+    // Very large numbers return unchanged
+    const large: f64 = 9007199254740992.0; // 2^53
+    try std.testing.expectEqual(large, rint(large));
+    try std.testing.expectEqual(-large, rint(-large));
+
+    // Small positive numbers round to zero
+    const pos_result = rint(0.3);
+    try std.testing.expectEqual(@as(f64, 0.0), pos_result);
+    try std.testing.expect(@as(u64, @bitCast(pos_result)) == 0);
+
+    // Small negative numbers round to negative zero
+    const neg_result = rint(-0.3);
+    try std.testing.expectEqual(@as(f64, 0.0), neg_result);
+    const bits: u64 = @bitCast(neg_result);
+    try std.testing.expect((bits >> 63) == 1);
+
+    // Exact half rounds to nearest even (banker's rounding)
+    try std.testing.expectEqual(@as(f64, 2.0), rint(2.5));
+    try std.testing.expectEqual(@as(f64, 4.0), rint(3.5));
+}
diff --git a/lib/libc/musl/src/math/rint.c b/lib/libc/musl/src/math/rint.c
deleted file mode 100644
index fbba390e7d723774d41ba2a9da74957c20643d63..0000000000000000000000000000000000000000
--- a/lib/libc/musl/src/math/rint.c
+++ /dev/null
@@ -1,28 +0,0 @@
-#include <float.h>
-#include <math.h>
-#include <stdint.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 rint(double x)
-{
-	union {double f; uint64_t i;} u = {x};
-	int e = u.i>>52 & 0x7ff;
-	int s = u.i>>63;
-	double_t y;
-
-	if (e >= 0x3ff+52)
-		return x;
-	if (s)
-		y = x - toint + toint;
-	else
-		y = x + toint - toint;
-	if (y == 0)
-		return s ? -0.0 : 0;
-	return y;
-}
diff --git a/lib/libc/musl/src/math/s390x/rint.c b/lib/libc/musl/src/math/s390x/rint.c
deleted file mode 100644
index b02f09eb0645ab577fe14471d76bc27f205823ba..0000000000000000000000000000000000000000
--- a/lib/libc/musl/src/math/s390x/rint.c
+++ /dev/null
@@ -1,15 +0,0 @@
-#include <math.h>
-
-#if defined(__HTM__) || __ARCH__ >= 9
-
-double rint(double x)
-{
-	__asm__ ("fidbr %0, 0, %1" : "=f"(x) : "f"(x));
-	return x;
-}
-
-#else
-
-#include "../rint.c"
-
-#endif
diff --git a/src/libs/musl.zig b/src/libs/musl.zig
index b201c1b7ff32e0ad63d15729618959f3fa543140..3f2739ec714d9d879bf73b340f55ac2b4d62e055 100644
--- a/src/libs/musl.zig
+++ b/src/libs/musl.zig
@@ -797,7 +797,6 @@ const src_files = [_][]const u8{
     "musl/src/math/aarch64/lroundf.c",
     "musl/src/math/aarch64/nearbyint.c",
     "musl/src/math/aarch64/nearbyintf.c",
-    "musl/src/math/aarch64/rint.c",
     "musl/src/math/aarch64/rintf.c",
     "musl/src/math/acosf.c",
     "musl/src/math/acosh.c",
@@ -887,7 +886,6 @@ const src_files = [_][]const u8{
     "musl/src/math/i386/remquof.s",
     "musl/src/math/i386/remquol.s",
     "musl/src/math/i386/remquo.s",
-    "musl/src/math/i386/rint.c",
     "musl/src/math/i386/rintf.c",
     "musl/src/math/i386/rintl.c",
     "musl/src/math/i386/scalblnf.s",
@@ -981,7 +979,6 @@ const src_files = [_][]const u8{
     "musl/src/math/remquo.c",
     "musl/src/math/remquof.c",
     "musl/src/math/remquol.c",
-    "musl/src/math/rint.c",
     "musl/src/math/rintf.c",
     "musl/src/math/rintl.c",
     "musl/src/math/riscv32/fma.c",
@@ -993,7 +990,6 @@ const src_files = [_][]const u8{
     "musl/src/math/s390x/nearbyint.c",
     "musl/src/math/s390x/nearbyintf.c",
     "musl/src/math/s390x/nearbyintl.c",
-    "musl/src/math/s390x/rint.c",
     "musl/src/math/s390x/rintf.c",
     "musl/src/math/s390x/rintl.c",
     "musl/src/math/scalb.c",
-- 
2.54.0