libdgl/DGLFIXP.C
Gered 62af8575c6 various updates i've left uncommitted for many months
- rename standard integer types to a more familiar (u)int(8/16/32)
- many function/struct renames. i don't _really_ know if what i've done
  for this is better, but it "feels" better to me. many draw/blit
  function names are shorter which is nice, at least. kinda important
  to me because i develop this on a real DOS machine in 80x50 text mode.
- add 'extern "C"' blocks to headers for C++ compiler usage
- draw/pixel color value arguments for functions should all have been
  changed to be uint8 instead of a full 32-bit int. feels right, but
  maybe should've left alone...
- small fix to keyboard handler. noticed a problem on one thinkpad
  laptop. was a result of what i think was a typo in a constant value
  used during the part of the interrupt handler that tells the keyboard
  controller the key event was processed
- fix uncommon potential crash function return in draw_filled_rect
- renamed low-level "direct" assembly functions to "lowlevel_xxx" to
  be a little bit more explicit about what they are
- add some convenience event helper functions for determining event
  types
- add fixed point atan2
- fixed some tabs/spaces inconsistences (should all be spaces now?)
- maybe some other minor things i've forgotten
2020-07-19 19:24:48 -04:00

38 lines
618 B
C
Executable file

#include "dglfixp.h"
fixed fix_sqrt(fixed x) {
int32 t, q, b, r;
r = x;
b = 0x40000000;
q = 0;
while (b > 0x40) {
t = q + b;
if (r >= t) {
r -= t;
q = t + b;
}
r <<= 1;
b >>= 1;
}
q >>= 8;
return q;
}
fixed fix_atan2(fixed y, fixed x) {
fixed absY, mask, angle, r, r3;
mask = (y >> (sizeof(fixed)*8-1));
absY = (y + mask) ^ mask;
if (x >= 0) {
r = fix_div(x - absY, x + absY);
} else {
r = fix_div(x + absY, absY - x);
}
return 0;
}