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

test/math/hypotf_test.c

@@ -0,0 +1,94 @@
+/*-*- 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 │
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2024 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ Permission to use, copy, modify, and/or distribute this software for         │
+│ any purpose with or without fee is hereby granted, provided that the         │
+│ above copyright notice and this permission notice appear in all copies.      │
+│                                                                              │
+│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
+│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
+│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
+│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
+│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
+│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
+│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
+│ PERFORMANCE OF THIS SOFTWARE.                                                │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include <errno.h>
+#include <limits.h>
+#include <math.h>
+
+#define OK 0
+
+#define MAX_ERROR_ULP 1
+
+#define CHECK(x) \
+  if (!(x)) return __LINE__
+
+#define TEST(e, x) \
+  errno = 0;       \
+  CHECK(x);        \
+  CHECK(errno == e)
+
+int rando(void) {
+  static unsigned long s;
+  s *= 6364136223846793005;
+  s += 1442695040888963407;
+  return s >> 32;
+}
+
+int main() {
+
+  // test base cases
+  TEST(OK, hypotf(3, 4) == 5);
+  TEST(OK, hypotf(0, 0) == 0);
+  TEST(OK, hypotf(5, 12) == 13);
+  TEST(OK, hypotf(-5, -12) == 13);
+  TEST(OK, hypotf(-3, 4) == 5);
+
+  // test with zeros
+  TEST(OK, hypotf(0, 0) == 0);
+  TEST(OK, hypotf(0, 3) == 3);
+  TEST(OK, hypotf(3, 0) == 3);
+
+  // test with NAN
+  TEST(OK, isnan(hypotf(NAN, 1)));
+  TEST(OK, isnan(hypotf(1, NAN)));
+  TEST(OK, isnan(hypotf(NAN, NAN)));
+
+  // test underflow avoidance
+  TEST(OK, hypotf(2e-38, 3e-38) > 0);
+
+  // test what happens on overflow
+  // TODO(jart): This should raise ERANGE.
+  TEST(OK, hypotf(FLT_MAX, FLT_MAX) == INFINITY);
+
+  // test with INFINITY
+  TEST(OK, hypotf(INFINITY, 1) == INFINITY);
+  TEST(OK, hypotf(1, INFINITY) == INFINITY);
+  TEST(OK, hypotf(-INFINITY, -INFINITY) == INFINITY);
+
+  // test accuracy assuming hypotl() is correct
+  union {
+    int i;
+    float f;
+  } x, y, a, b;
+  int n = 1000;
+  for (int i = 0; i < n; ++i) {
+    for (int j = 0; j < n; ++j) {
+      x.i = rando();
+      y.i = rando();
+      a.f = hypotl(x.f, y.f);
+      b.f = hypotf(x.f, y.f);
+      if (isnan(a.f) || isnan(b.f)) {
+        CHECK(isnan(a.f) == isnan(b.f));
+        continue;
+      }
+      long e = b.i - a.i;
+      if (e < 0) e = -e;
+      CHECK(e <= MAX_ERROR_ULP);
+    }
+  }
+}