[util] Support parsing floating point arguments

src/util/config/config.cpp

@@ -755,6 +755,66 @@ namespace dxvk {
   }
   
   
+  bool Config::parseOptionValue(
+    const std::string&  value,
+          float&        result) {
+    if (value.size() == 0)
+      return false;
+
+    // Parse sign
+    size_t pos = 0;
+    bool negate = false;
+
+    if (value[0] == '-') {
+      negate = true;
+      pos += 1;
+    }
+
+    // Parse integer part
+    uint64_t intPart = 0;
+
+    if (value[pos] == '.')
+      return false;
+
+    while (pos < value.size()) {
+      if (value[pos] == '.') {
+        if (++pos == value.size())
+          return false;
+        break;
+      }
+
+      if (value[pos] < '0' || value[pos] > '9')
+        return false;
+
+      intPart *= 10;
+      intPart += value[pos] - '0';
+      pos += 1;
+    }
+
+    // Parse fractional part
+    uint64_t fractPart = 0;
+    uint64_t fractDivisor = 1;
+
+    while (pos < value.size()) {
+      if (value[pos] < '0' || value[pos] > '9')
+        return false;
+
+      fractDivisor *= 10;
+      fractPart *= 10;
+      fractPart += value[pos] - '0';
+      pos += 1;
+    }
+
+    // Compute final number, not super accurate but this should do
+    result = float((double(fractPart) / double(fractDivisor)) + double(intPart));
+
+    if (negate)
+      result = -result;
+
+    return true;
+  }
+
+
   bool Config::parseOptionValue(
     const std::string&  value,
           Tristate&     result) {

src/util/config/config.h

@@ -123,6 +123,10 @@ namespace dxvk {
       const std::string&  value,
             int32_t&      result);
     
+    static bool parseOptionValue(
+      const std::string&  value,
+            float&        result);
+
     static bool parseOptionValue(
       const std::string&  value,
             Tristate&     result);