Update MentOs code to the latest development version.

libc/src/fcvt.c

@@ -0,0 +1,104 @@
+///                MentOS, The Mentoring Operating system project
+/// @file fcvt.c
+/// @brief Define the functions required to turn double values into a string.
+/// @copyright (c) 2014-2021 This file is distributed under the MIT License.
+/// See LICENSE.md for details.
+
+#include "fcvt.h"
+#include "math.h"
+
+static void cvt(double arg, int ndigits, int *decpt, int *sign, char *buf, unsigned buf_size, int eflag)
+{
+    int r2;
+    double fi, fj;
+    char *p, *p1;
+
+    char *buf_end = (buf + buf_size);
+
+    if (ndigits < 0) {
+        ndigits = 0;
+    }
+
+    if (ndigits >= buf_size - 1) {
+        ndigits = buf_size - 2;
+    }
+
+    r2    = 0;
+    *sign = 0;
+    p     = &buf[0];
+
+    if (arg < 0) {
+        *sign = 1;
+        arg   = -arg;
+    }
+
+    arg = modf(arg, &fi);
+    p1  = buf_end;
+
+    if (fi != 0) {
+        p1 = buf_end;
+        while (fi != 0) {
+            fj    = modf(fi / 10, &fi);
+            *--p1 = (int)((fj + .03) * 10) + '0';
+            r2++;
+        }
+        while (p1 < buf_end) {
+            *p++ = *p1++;
+        }
+    } else if (arg > 0) {
+        while ((fj = arg * 10) < 1) {
+            arg = fj;
+            r2--;
+        }
+    }
+
+    p1 = &buf[ndigits];
+    if (eflag == 0) {
+        p1 += r2;
+    }
+
+    *decpt = r2;
+    if (p1 < &buf[0]) {
+        buf[0] = '\0';
+        return;
+    }
+
+    while (p <= p1 && p < buf_end) {
+        arg *= 10;
+        arg  = modf(arg, &fj);
+        *p++ = (int)fj + '0';
+    }
+
+    if (p1 >= buf_end) {
+        buf[buf_size - 1] = '\0';
+        return;
+    }
+
+    p = p1;
+    *p1 += 5;
+    while (*p1 > '9') {
+        *p1 = '0';
+        if (p1 > buf) {
+            ++*--p1;
+        } else {
+            *p1 = '1';
+            (*decpt)++;
+            if (eflag == 0) {
+                if (p > buf)
+                    *p = '0';
+                p++;
+            }
+        }
+    }
+    *p = '\0';
+}
+
+void ecvtbuf(double arg, int chars, int *decpt, int *sign, char *buf, unsigned buf_size)
+{
+    cvt(arg, chars, decpt, sign, buf, buf_size, 1);
+}
+
+void fcvtbuf(double arg, int decimals, int *decpt, int *sign, char *buf, unsigned buf_size)
+{
+    cvt(arg, decimals, decpt, sign, buf, buf_size, 0);
+}