From 3f0be4e9ea637b97f8f1e13e83d50ebbf34edaa5 Mon Sep 17 00:00:00 2001
From: Peter Elliott <pelliott@ualberta.ca>
Date: Sat, 7 May 2022 12:17:04 -0600
Subject: [PATCH] LibC: Add barebones <complex.h>

---
 Userland/Libraries/LibC/CMakeLists.txt |  1 +
 Userland/Libraries/LibC/complex.cpp    | 46 ++++++++++++++++++++++++++
 Userland/Libraries/LibC/complex.h      | 44 ++++++++++++++++++++++++
 3 files changed, 91 insertions(+)
 create mode 100644 Userland/Libraries/LibC/complex.cpp
 create mode 100644 Userland/Libraries/LibC/complex.h

diff --git a/Userland/Libraries/LibC/CMakeLists.txt b/Userland/Libraries/LibC/CMakeLists.txt
index 2f8a603cb6f..885bbcbb3d5 100644
--- a/Userland/Libraries/LibC/CMakeLists.txt
+++ b/Userland/Libraries/LibC/CMakeLists.txt
@@ -1,6 +1,7 @@
 set(LIBC_SOURCES
     arpa/inet.cpp
     assert.cpp
+    complex.cpp
     ctype.cpp
     cxxabi.cpp
     dirent.cpp
diff --git a/Userland/Libraries/LibC/complex.cpp b/Userland/Libraries/LibC/complex.cpp
new file mode 100644
index 00000000000..6820e03dab7
--- /dev/null
+++ b/Userland/Libraries/LibC/complex.cpp
@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2022, Peter Elliott <pelliott@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <complex.h>
+
+extern "C" {
+
+// Function definitions of this form "type (name)(args)" are intentional, to
+// prevent macro versions of "name" from being incorrectly expanded. These
+// functions are here to provide external linkage to their macro implementations.
+
+// https://pubs.opengroup.org/onlinepubs/9699919799/functions/creal.html
+float(crealf)(float complex z)
+{
+    return crealf(z);
+}
+
+double(creal)(double complex z)
+{
+    return creal(z);
+}
+
+long double(creall)(long double complex z)
+{
+    return creall(z);
+}
+
+// https://pubs.opengroup.org/onlinepubs/9699919799/functions/cimag.html
+double(cimag)(double complex z)
+{
+    return cimag(z);
+}
+
+float(cimagf)(float complex z)
+{
+    return cimagf(z);
+}
+
+long double(cimagl)(long double complex z)
+{
+    return cimagl(z);
+}
+}
diff --git a/Userland/Libraries/LibC/complex.h b/Userland/Libraries/LibC/complex.h
new file mode 100644
index 00000000000..a3b718e1f4a
--- /dev/null
+++ b/Userland/Libraries/LibC/complex.h
@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2022, Peter Elliott <pelliott@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+/* complex arithmetic
+ *
+ * https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/complex.h.html
+ */
+
+#pragma once
+
+#include <stddef.h>
+
+__BEGIN_DECLS
+
+#define complex _Complex
+
+#define _Complex_I (0.0f + 1.0fi)
+#define I _Complex_I
+
+#define CMPLX(x, y) ((double complex)__builtin_complex((double)x, (double)y))
+#define CMPLXF(x, y) ((float complex)__builtin_complex((float)x, (float)y))
+#define CMPLXL(x, y) ((long double complex)__builtin_complex((long double)x, (long double)y))
+
+float crealf(float complex z);
+double creal(double complex z);
+long double creall(long double complex z);
+
+double cimag(double complex z);
+float cimagf(float complex z);
+long double cimagl(long double complex z);
+
+// These are macro implementations of the above functions, so that they will always be inlined.
+#define creal(z) ((double)__real__((double complex)z))
+#define crealf(z) ((float)__real__((float complex)z))
+#define creall(z) ((long double)__real__((long double complex)z))
+
+#define cimag(z) ((double)__imag__((double complex)z))
+#define cimagf(z) ((float)__imag__((float complex)z))
+#define cimagl(z) ((long double)__imag__((long double complex)z))
+
+__END_DECLS