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[calc.git] / fdprintf.c

diff --git a/fdprintf.c b/fdprintf.c
index 1bc1b1907a0de6f82d320a015d562131c39cb7ad..46f27acb8f6b7a05032a4bd5d1038f90011b6061 100644 (file)
--- a/fdprintf.c
+++ b/fdprintf.c
@@ -43,6 +43,38 @@ char *itoa (char *str, unsigned u, unsigned int sz)
     return s;
 }
 
+double tenpower(int n)
+{
+    double t = 1.0;
+    int i;
+    for (i = 0; i < n; i++) {
+        t *= 10;
+    }
+    for (i = 0; i > n; i--) {
+        t /= 10;
+    }
+    return t;
+}
+
+int getexponant (double *f, int maxexp)
+{
+    int exp = 0;
+    while (*f > 10) {
+        *f /= 10;
+        exp++;
+    }
+    while (*f < 1) {
+        *f *= 10;
+        exp--;
+    }
+    *f += tenpower (maxexp - 1);
+    if (*f >= 10) {
+        *f /= 10;
+        exp++;
+    }
+
+    return exp;
+}
 /* simple fprintf function */
 
 int fdprintf (int fd, const char *fmt, ...)
@@ -64,7 +96,7 @@ int fdprintf (int fd, const char *fmt, ...)
             *str++ = c;
         } else {
             int t = 0;
-           char w = '0';
+            char w = '0';
             int i, sz = 0;
             void *p = NULL;
 
@@ -80,6 +112,9 @@ int fdprintf (int fd, const char *fmt, ...)
 
             /* process format char */
             switch (*fmt++) {
+            case '%': /* percent */
+                *str++ = '%';
+                break;
             case 'c': /* char */
                 c = (char) va_arg (ap, int);
                 *str++ = c;
@@ -97,30 +132,25 @@ int fdprintf (int fd, const char *fmt, ...)
                 break;
             case 'f': /* float */
                 f = va_arg (ap, double);
+                if (f == 0) {
+                    *str++ = '0';
+                    break;
+                }
                 if (f < 0) {
                     *str++ = '-';
                     f = -f;
                 }
-                t = 0;
-                while (f > 10) {
-                    f /= 10;
-                    t++;
-                }
-                while (f < 1) {
-                    f *= 10;
-                    t--;
-                }
-               f += 1e-7;
-                if (f >= 10) {
-                    f /= 10;
-                    t++;
-                }
+                if (sz == 0) sz = 6;
+                t = getexponant (&f, -sz);
                 u = (int)f;
                 str = itoa (str, u, 0);
-                d = (int)((f - u) * 1e6);
+                d = (int)((f - u) * tenpower (sz));
                 if (d > 0) {
                     *str++ = '.';
-                    str = itoa (str, d, 6);
+                    str = itoa (str, d, sz);
+                }
+                while (*(str - 1) == '0') {
+                    str--;
                 }
                 if (t != 0) {
                     *str++ = 'e';