pxt-calliope/libs/microbit/core.cpp

#include "ksbit.h"
#include <limits.h>

namespace StringMethods {

    /**
      * Returns the character at the specified index.
      * @param pos The zero-based index of the desired character.
      */
    //%
    StringData *charAt(StringData *s, int pos) {
      return ManagedString((char)ManagedString(s).charAt(pos)).leakData();
    }

    /** 
      * Returns the Unicode value of the character at the specified location.
      * @param index The zero-based index of the desired character. If there is no character at the specified index, NaN is returned.
      */
    //%
    int charCodeAt(StringData *s, int index) {
      return ManagedString(s).charAt(index);
    }

    /**
      * Returns a string that contains the concatenation of two or more strings.
      * @param other The string to append to the end of the string.  
      */
    //%
    StringData *concat(StringData *s, StringData *other) {
      ManagedString a(s), b(other);
      return (a + b).leakData();
    }

    /**
      * Determines whether relative order of two strings (in ASCII encoding).
      * @param that String to compare to target string
      */
    //%
    int compare(StringData *s, StringData *that) {
        return strcmp(s->data, that->data);
    }

    /** Returns the length of a String object. */
    //% property
    int length(StringData *s) {
        return s->len;
    }
}


namespace BooleanMethods {
    // Cache the string literals "true" and "false" when used.
    // Note that the representation of booleans stays the usual C-one.
    
    static const char sTrue[]  __attribute__ ((aligned (4))) = "\xff\xff\x04\x00" "true\0";
    static const char sFalse[] __attribute__ ((aligned (4))) = "\xff\xff\x05\x00" "false\0";

    /**
      * Returns a string representation of an object.
      */
    //%
    StringData* toString(bool v)
    {
      if (v) {
        return (StringData*)(void*)sTrue;
      } else {
        return (StringData*)(void*)sFalse;
      }            
    }
}

namespace String {
    /**
      * Make a string from the given ASCII character code. 
      */
    //%
    StringData *fromCharCode(int code)
    {
      return ManagedString((char)code).leakData();
    }
}

namespace NumberMethods {
    /**
      * Returns a string representation of a number.
      */
    //%
    StringData* toString(int n)
    {
      return ManagedString(n).leakData();
    }
}

namespace Math {
    /**
      * Returns the value of a base expression taken to a specified power. 
      * @param x The base value of the expression.
      * @param y The exponent value of the expression.
      */
    //%
    int pow(int x, int y)
    {
      if (y < 0)
        return 0;
      int r = 1;
      while (y) {
        if (y & 1)
          r *= x;
        y >>= 1;
        x *= x;
      }
      return r;
    }
    
    /** 
     * Returns a pseudorandom number between 0 and `max`. 
     */
    //%
    int random(int max) {
      if (max == INT_MIN)
        return -uBit.random(INT_MAX);
      else if (max < 0)
        return -uBit.random(-max);
      else if (max == 0)
        return 0;
      else
        return uBit.random(max);
    }
    
    /**
      * Returns the square root of a number.
      * @param x A numeric expression.
      */
    //%
    int sqrt(int x)
    {
      return ::sqrt(x);
    }
}