Removed again lots of arduino bullshit

src/widgets/vumeter.cpp

@@ -2,10 +2,10 @@
 
 // system includes
 #include <cmath>
+#include <cstring>
 
 // 3rdparty lib includes
 #include <cpputils.h>
-#include <stdlib_noniso.h>
 #include <fontrenderer.h>
 
 // local includes
@@ -104,6 +104,81 @@ void VuMeter::start(TftInterface &tft)
     tft.drawRect(5, 3, 230, 119, TFT_BLACK); // Draw bezel line
 }
 
+namespace {
+char * dtostrf(double number, signed char width, unsigned char prec, char *s) {
+    bool negative = false;
+
+    if (std::isnan(number)) {
+        std::strcpy(s, "nan");
+        return s;
+    }
+    if (std::isinf(number)) {
+        std::strcpy(s, "inf");
+        return s;
+    }
+
+    char* out = s;
+
+    int fillme = width; // how many cells to fill for the integer part
+    if (prec > 0) {
+        fillme -= (prec+1);
+    }
+
+    // Handle negative numbers
+    if (number < 0.0) {
+        negative = true;
+        fillme--;
+        number = -number;
+    }
+
+    // Round correctly so that print(1.999, 2) prints as "2.00"
+    // I optimized out most of the divisions
+    double rounding = 2.0;
+    for (uint8_t i = 0; i < prec; ++i)
+        rounding *= 10.0;
+    rounding = 1.0 / rounding;
+
+    number += rounding;
+
+    // Figure out how big our number really is
+    double tenpow = 1.0;
+    int digitcount = 1;
+    while (number >= 10.0 * tenpow) {
+        tenpow *= 10.0;
+        digitcount++;
+    }
+
+    number /= tenpow;
+    fillme -= digitcount;
+
+    // Pad unused cells with spaces
+    while (fillme-- > 0) {
+        *out++ = ' ';
+    }
+
+    // Handle negative sign
+    if (negative) *out++ = '-';
+
+    // Print the digits, and if necessary, the decimal point
+    digitcount += prec;
+    int8_t digit = 0;
+    while (digitcount-- > 0) {
+        digit = (int8_t)number;
+        if (digit > 9) digit = 9; // insurance
+        *out++ = (char)('0' | digit);
+        if ((digitcount == prec) && (prec > 0)) {
+            *out++ = '.';
+        }
+        number -= digit;
+        number *= 10.0;
+    }
+
+    // make sure the string is terminated
+    *out = 0;
+    return s;
+}
+}
+
 void VuMeter::redraw(TftInterface &tft, float value)
 {
     FontRenderer fontRenderer{tft};