From 521a093334eb92b4fd2430b9018ed94b912857a8 Mon Sep 17 00:00:00 2001
From: mihael <hi@mihaelm.com>
Date: Wed, 18 Mar 2026 23:02:53 +0100
Subject: [PATCH] `libzigc/math`: Implement `frexpf`

The `frexp` implementation was generalized so it can be used for `f32`
and `c_longdouble` types as well.

The changes were tested by running:

```
$ ./build/stage3/bin/zig build -p stage4 -Denable-llvm -Dno-lib

$ stage4/bin/zig build test-libc -Dlibc-test-path=<LIBC-TEST-PATH> -Dtest-filter=frexp -fqemu -fwasmtime --summary line
Build Summary: 737/737 steps succeeded

$ stage4/bin/zig build test-libc -Dlibc-test-path=<LIBC-TEST-PATH> -Dtest-filter=frexpf -fqemu -fwasmtime --summary line
Build Summary: 369/369 steps succeeded
```
---
 lib/c/math.zig                  | 13 +++++++++++--
 lib/libc/mingw/math/frexpf.c    | 13 -------------
 lib/libc/musl/src/math/frexpf.c | 23 -----------------------
 src/libs/mingw.zig              |  1 -
 src/libs/musl.zig               |  1 -
 src/libs/wasi_libc.zig          |  1 -
 6 files changed, 11 insertions(+), 41 deletions(-)
 delete mode 100644 lib/libc/mingw/math/frexpf.c
 delete mode 100644 lib/libc/musl/src/math/frexpf.c

diff --git a/lib/c/math.zig b/lib/c/math.zig
index 8fe93716dbebc34bf2bc5276d764c4e93ffd8a16..1f379792a7c61145815193c33496872e118ea38b 100644
--- a/lib/c/math.zig
+++ b/lib/c/math.zig
@@ -36,6 +36,7 @@ comptime {
 
     if (builtin.target.isMinGW() or builtin.target.isMuslLibC() or builtin.target.isWasiLibC()) {
         symbol(&coshf, "coshf");
+        symbol(&frexpf, "frexpf");
         symbol(&hypotf, "hypotf");
         symbol(&hypotl, "hypotl");
         symbol(&modff, "modff");
@@ -162,7 +163,7 @@ fn fdim(x: f64, y: f64) callconv(.c) f64 {
     return 0;
 }
 
-fn frexp(x: f64, e: *c_int) callconv(.c) f64 {
+fn frexpGeneric(comptime T: type, x: T, e: *c_int) T {
     // libc expects `*e` to be unspecified in this case; an unspecified C value
     // should be a valid value of the relevant type, yet Zig's std
     // implementation sets it to `undefined` -- which can even be nonsense
@@ -170,7 +171,7 @@ fn frexp(x: f64, e: *c_int) callconv(.c) f64 {
     // int value in Zig -- a zero.
     //
     // This mirrors the handling of infinities, where libc also expects
-    // unspecified for the value `*e` and Zig std sets it to a zero.
+    // unspecified for the value of `*e` and Zig std sets it to a zero.
     if (math.isNan(x)) {
         e.* = 0;
         return x;
@@ -181,6 +182,14 @@ fn frexp(x: f64, e: *c_int) callconv(.c) f64 {
     return r.significand;
 }
 
+fn frexp(x: f64, e: *c_int) callconv(.c) f64 {
+    return frexpGeneric(f64, x, e);
+}
+
+fn frexpf(x: f32, e: *c_int) callconv(.c) f32 {
+    return frexpGeneric(f32, x, e);
+}
+
 fn hypot(x: f64, y: f64) callconv(.c) f64 {
     return math.hypot(x, y);
 }
diff --git a/lib/libc/mingw/math/frexpf.c b/lib/libc/mingw/math/frexpf.c
deleted file mode 100644
index d4b7ab36c20475e51168a19909bfd643e4bac1fa..0000000000000000000000000000000000000000
--- a/lib/libc/mingw/math/frexpf.c
+++ /dev/null
@@ -1,13 +0,0 @@
-/**
- * This file has no copyright assigned and is placed in the Public Domain.
- * This file is part of the mingw-w64 runtime package.
- * No warranty is given; refer to the file DISCLAIMER.PD within this package.
- */
-extern double __cdecl frexp(double _X,int *_Y);
-
-float frexpf (float, int *);
-float frexpf (float x, int *expn)
-{
-  return (float)frexp(x, expn);
-}
-
diff --git a/lib/libc/musl/src/math/frexpf.c b/lib/libc/musl/src/math/frexpf.c
deleted file mode 100644
index 0787097527c22a4be256abb600b9a05061a2ec87..0000000000000000000000000000000000000000
--- a/lib/libc/musl/src/math/frexpf.c
+++ /dev/null
@@ -1,23 +0,0 @@
-#include <math.h>
-#include <stdint.h>
-
-float frexpf(float x, int *e)
-{
-	union { float f; uint32_t i; } y = { x };
-	int ee = y.i>>23 & 0xff;
-
-	if (!ee) {
-		if (x) {
-			x = frexpf(x*0x1p64, e);
-			*e -= 64;
-		} else *e = 0;
-		return x;
-	} else if (ee == 0xff) {
-		return x;
-	}
-
-	*e = ee - 0x7e;
-	y.i &= 0x807ffffful;
-	y.i |= 0x3f000000ul;
-	return y.f;
-}
diff --git a/src/libs/mingw.zig b/src/libs/mingw.zig
index f7b73cc96e8db83c8012be02c561b98c8b082ede..e9417eb9454b22a88ac4a4c9576b7ad6871576df 100644
--- a/src/libs/mingw.zig
+++ b/src/libs/mingw.zig
@@ -613,7 +613,6 @@ const mingw32_generic_src = [_][]const u8{
     "math" ++ path.sep_str ++ "fpclassify.c",
     "math" ++ path.sep_str ++ "fpclassifyf.c",
     "math" ++ path.sep_str ++ "fpclassifyl.c",
-    "math" ++ path.sep_str ++ "frexpf.c",
     "math" ++ path.sep_str ++ "frexpl.c",
     "math" ++ path.sep_str ++ "ldexpf.c",
     "math" ++ path.sep_str ++ "lgamma.c",
diff --git a/src/libs/musl.zig b/src/libs/musl.zig
index e90a08f92c5f62a570728a76f27778160b88f8e4..86e0995220842f3d6b35442c2bc497df26384522 100644
--- a/src/libs/musl.zig
+++ b/src/libs/musl.zig
@@ -839,7 +839,6 @@ const src_files = [_][]const u8{
     "musl/src/math/__fpclassify.c",
     "musl/src/math/__fpclassifyf.c",
     "musl/src/math/__fpclassifyl.c",
-    "musl/src/math/frexpf.c",
     "musl/src/math/frexpl.c",
     "musl/src/math/i386/acosl.s",
     "musl/src/math/i386/asinf.s",
diff --git a/src/libs/wasi_libc.zig b/src/libs/wasi_libc.zig
index d694a0381e385a5ed35b2cb27a0e25e9e144acf3..d0743dbe3d10334e7aeafbef8c71bc3ae7043195 100644
--- a/src/libs/wasi_libc.zig
+++ b/src/libs/wasi_libc.zig
@@ -701,7 +701,6 @@ const libc_top_half_src_files = [_][]const u8{
     "musl/src/math/finitef.c",
     "musl/src/math/fma.c",
     "musl/src/math/fmaf.c",
-    "musl/src/math/frexpf.c",
     "musl/src/math/frexpl.c",
     "musl/src/math/ilogb.c",
     "musl/src/math/ilogbf.c",
-- 
2.54.0