Make quality improvements

- Write some more unit tests
- memcpy() on ARM is now faster
- Address the Musl complex math FIXME comments
- Some libm funcs like pow() now support setting errno
- Import the latest and greatest math functions from ARM
- Use more accurate atan2f() and log1pf() implementations
- atoi() and atol() will no longer saturate or clobber errno

libc/tinymath/erff_data.c

@@ -0,0 +1,43 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8                               :vi │
+╚──────────────────────────────────────────────────────────────────────────────╝
+│                                                                              │
+│  Optimized Routines                                                          │
+│  Copyright (c) 2018-2024, Arm Limited.                                       │
+│                                                                              │
+│  Permission is hereby granted, free of charge, to any person obtaining       │
+│  a copy of this software and associated documentation files (the             │
+│  "Software"), to deal in the Software without restriction, including         │
+│  without limitation the rights to use, copy, modify, merge, publish,         │
+│  distribute, sublicense, and/or sell copies of the Software, and to          │
+│  permit persons to whom the Software is furnished to do so, subject to       │
+│  the following conditions:                                                   │
+│                                                                              │
+│  The above copyright notice and this permission notice shall be              │
+│  included in all copies or substantial portions of the Software.             │
+│                                                                              │
+│  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,             │
+│  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF          │
+│  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.      │
+│  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY        │
+│  CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,        │
+│  TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE           │
+│  SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                      │
+│                                                                              │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/tinymath/arm.internal.h"
+__static_yoink("arm_optimized_routines_notice");
+
+/* Minimax approximation of erff. */
+const struct erff_data __erff_data = {
+.erff_poly_A = {
+0x1.06eba6p-03f, -0x1.8126e0p-02f, 0x1.ce1a46p-04f,
+-0x1.b68bd2p-06f, 0x1.473f48p-08f, -0x1.3a1a82p-11f
+},
+.erff_poly_B = {
+0x1.079d0cp-3f, 0x1.450aa0p-1f, 0x1.b55cb0p-4f,
+-0x1.8d6300p-6f, 0x1.fd1336p-9f, -0x1.91d2ccp-12f,
+0x1.222900p-16f
+}
+};
+