Add fixes performance and static web server

libc/fmt/fcvt.c

@@ -0,0 +1,128 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2009 Ian Piumarta                                                  │
+│                                                                              │
+│ 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, and/or sell copies  │
+│ of the Software, and to permit persons to whom the Software is furnished to  │
+│ do so, provided that the above copyright notice(s) and this permission       │
+│ notice appear in all copies of the Software.  Inclusion of the above         │
+│ copyright notice(s) and this permission notice in supporting documentation   │
+│ would be appreciated but is not required.                                    │
+│                                                                              │
+│ THE SOFTWARE IS PROVIDED 'AS IS'.  USE ENTIRELY AT YOUR OWN RISK.            │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/assert.h"
+#include "libc/fmt/fmt.h"
+#include "libc/macros.h"
+#include "libc/math.h"
+#include "libc/runtime/runtime.h"
+#include "libc/str/str.h"
+
+asm(".ident\t\"\\n\\n\
+ecvt, fcvt (MIT License)\\n\
+Copyright 2009 Ian Piumarta\"");
+
+/**
+ * @fileoverview Replacements for the functions ecvt() and fcvt()
+ *
+ * These functions were recently deprecated in POSIX. The interface and
+ * behaviour is identical to the functions that they replace and faster.
+ *
+ * For details on the use of these functions, see your ecvt(3) manual
+ * page. If you don't have one handy, there might still be one available
+ * here: http://opengroup.org/onlinepubs/007908799/xsh/ecvt.html
+ *
+ * @see https://www.piumarta.com/software/fcvt/
+ */
+
+static char *Fcvt(double value, int ndigit, int *decpt, int *sign, int fflag) {
+  static char buf[128];
+  double i;
+  uint64_t l, mant;
+  int exp2, exp10, ptr;
+  memcpy(&l, &value, 8);
+  exp2 = (0x7ff & (l >> 52)) - 1023;
+  mant = l & 0x000fffffffffffffULL;
+  if ((*sign = l >> 63)) value = -value;
+  if (exp2 == 0x400) {
+    *decpt = 0;
+    return mant ? "nan" : "inf";
+  }
+  exp10 = (value == 0) ? !fflag : (int)ceil(log10(value));
+  if (exp10 < -307) exp10 = -307; /* otherwise overflow in pow() */
+  value *= pow(10.0, -exp10);
+  if (value) {
+    while (value < 0.1) {
+      value *= 10;
+      --exp10;
+    }
+    while (value >= 1.0) {
+      value /= 10;
+      ++exp10;
+    }
+  }
+  assert(value == 0 || (0.1 <= value && value < 1.0));
+  if (fflag) {
+    if (ndigit + exp10 < 0) {
+      *decpt = -ndigit;
+      return "";
+    }
+    ndigit += exp10;
+  }
+  *decpt = exp10;
+  if (ARRAYLEN(buf) < ndigit + 2) abort();
+  ptr = 1;
+#if 0 /* slow and safe (and dreadfully boring) */
+  while (ptr <= ndigit) {
+    i;
+    value = modf(value * 10, &i);
+    buf[ptr++] = '0' + (int)i;
+  }
+  if (value >= 0.5) {
+    while (--ptr && ++buf[ptr] > '9') {
+      buf[ptr] = '0';
+    }
+  }
+#else /* faster */
+  memcpy(&l, &value, 8);
+  exp2 = (0x7ff & (l >> 52)) - 1023;
+  assert(value == 0 || (-4 <= exp2 && exp2 <= -1));
+  mant = l & 0x000fffffffffffffULL;
+  if (exp2 == -1023) {
+    ++exp2;
+  } else {
+    mant |= 0x0010000000000000ULL;
+  }
+  mant <<= (exp2 + 4); /* 56-bit denormalised signifier */
+  while (ptr <= ndigit) {
+    mant &= 0x00ffffffffffffffULL; /* mod 1.0 */
+    mant = (mant << 1) + (mant << 3);
+    buf[ptr++] = '0' + (mant >> 56);
+  }
+  if (mant & 0x0080000000000000ULL) /* 1/2 << 56 */
+    while (--ptr && ++buf[ptr] > '9') buf[ptr] = '0';
+#endif
+  if (ptr) {
+    buf[ndigit + 1] = 0;
+    return buf + 1;
+  }
+  if (fflag) {
+    ++ndigit;
+    ++*decpt;
+  }
+  buf[0] = '1';
+  buf[ndigit] = 0;
+  return buf;
+}
+
+char *ecvt(double value, int ndigit, int *decpt, int *sign) {
+  return Fcvt(value, ndigit, decpt, sign, 0);
+}
+
+char *fcvt(double value, int ndigit, int *decpt, int *sign) {
+  return Fcvt(value, ndigit, decpt, sign, 1);
+}