About the library source code

[Chingson Chen]

I see the library code seems mostly done in 1999. The code works, but it feels me a little dump after some checking.
For example, the "_divuint"

 do
  {
    // reste: x <- 0;
   ** c = MSB_SET(x);
    x <<= 1;
    reste <<= 1;
    if (c)
      reste |= 1;**

    if (reste >= y)
    {
      reste -= y;
      // x <- (result = 1)
      x |= 1;
    }
  }

will it be equal to

 do
  {
    // reste: x <- 0;

    **reste <<= 1;
    if (MSB_SET(x))
      reste |= 1;
    x<<=1;**

    if (reste >= y)
    {
      reste -= y;
      // x <- (result = 1)
      x |= 1;
    }
  }
// which saves a variable and some lines of codes

also the _mod operation

**while (!MSB_SET(b))
  {
    b <<= 1;
    if (b > a)
    {
      b >>=1;
      break;
    }
    count++;
  }**
  do
  {
    if (a >= b)
      a -= b;
    b >>= 1;
  }
  while (count--);

why not write as

**while (!MSB_SET(b) && b<=a)
  {
    b <<= 1;
    count++;
  }
**  do
  {
    if (a >= b)
      a -= b;
    b >>= 1;
  }

// this also saves a right shift of b

Though several bytes of code will not effect the correctness, shorter code let embedded systems enters sleep mode earlier and saves energy, which also saves our earth.

Just ..free discussion.

Chingson

[Maarten Brock]

But is the generated asm also shorter and/or faster? Shorter C does not automatically mean better asm. For which target are you compiling?

[Chingson Chen]

In "_divuxxx", assignment of "c" is hard to be optimized. Also, in "__moduxxx", shift left (<<) is also hard to be optimized. Yes, we will get shorter code, at least for PIC series.