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Add POS_MOD macro and use for all positive modulos

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This macro is to make it so it won't be error-prone to write the
semi-confusing `(a % b + b) % b` statement, and you can just use an easy
macro instead.

Currently, the only places a positive modulo is needed is when switching
tilesets, enemies, and warp directions in the editor, as well as when
getting a tile in the tower, since towers just repeat themselves
vertically. Towers used this weird while-loop to sort of emulate a
modulo, which isn't half-bad, but is unnecessary, and I don't think any
compiler would recognize it as a modulo. (And if it's not optimized to a
proper modulo... what happens if the number being moduloed is really,
really big?)
This commit is contained in:
Misa 2021-09-24 17:48:15 -07:00
parent 891ca527f9
commit cace685020
3 changed files with 12 additions and 9 deletions
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6
desktop_version/src/Editor.cpp
View file

@ -4175,7 +4175,7 @@ void editorclass::switch_tileset(const bool reversed)
} }
const int modulus = SDL_arraysize(tilesets); const int modulus = SDL_arraysize(tilesets);
tiles = (tiles % modulus + modulus) % modulus; tiles = POS_MOD(tiles, modulus);
cl.setroomtileset(levx, levy, tiles); cl.setroomtileset(levx, levy, tiles);
clamp_tilecol(levx, levy, false); clamp_tilecol(levx, levy, false);
@ -4270,7 +4270,7 @@ void editorclass::switch_enemy(const bool reversed)
} }
const int modulus = 10; const int modulus = 10;
enemy = (enemy % modulus + modulus) % modulus; enemy = POS_MOD(enemy, modulus);
cl.setroomenemytype(levx, levy, enemy); cl.setroomenemytype(levx, levy, enemy);
note = "Enemy Type Changed"; note = "Enemy Type Changed";
@ -4293,7 +4293,7 @@ void editorclass::switch_warpdir(const bool reversed)
++warpdir; ++warpdir;
} }
warpdir = (warpdir % modulus + modulus) % modulus; warpdir = POS_MOD(warpdir, modulus);
cl.setroomwarpdir(levx, levy, warpdir); cl.setroomwarpdir(levx, levy, warpdir);
switch (warpdir) switch (warpdir)

10
desktop_version/src/Tower.cpp
View file

@ -5,6 +5,7 @@
#include "Constants.h" #include "Constants.h"
#include "MakeAndPlay.h" #include "MakeAndPlay.h"
#include "UtilityClass.h"
towerclass::towerclass(void) towerclass::towerclass(void)
{ {
@ -24,8 +25,7 @@ int towerclass::backat(int xp, int yp, int yoff)
if (xp >= 0 && xp < 40) if (xp >= 0 && xp < 40)
{ {
while (yp < 0) yp += 120; yp = POS_MOD(yp, 120);
while (yp >= 120) yp -= 120;
return back[TILE_IDX(xp, yp)]; return back[TILE_IDX(xp, yp)];
} }
return 0; return 0;
@ -41,8 +41,7 @@ int towerclass::at(int xp, int yp, int yoff)
{ {
yp = (yp*8 + yoff) / 8; yp = (yp*8 + yoff) / 8;
while (yp < 0) yp += 700; yp = POS_MOD(yp, 700);
while (yp >= 700) yp -= 700;
if (xp >= 0 && xp < 40) if (xp >= 0 && xp < 40)
{ {
return contents[TILE_IDX(xp, yp)]; return contents[TILE_IDX(xp, yp)];
@ -63,8 +62,7 @@ int towerclass::miniat(int xp, int yp, int yoff)
{ {
yp = (yp*8 + yoff) / 8; yp = (yp*8 + yoff) / 8;
while (yp < 0) yp += 100; yp = POS_MOD(yp, 100);
while (yp >= 100) yp -= 100;
if (xp >= 0 && xp < 40) if (xp >= 0 && xp < 40)
{ {
return minitower[TILE_IDX(xp, yp)]; return minitower[TILE_IDX(xp, yp)];

5
desktop_version/src/UtilityClass.h
View file

@ -88,6 +88,11 @@ void _VVV_between(
} \ } \
while (false) while (false)
/* Positive modulo, because C/C++'s modulo operator sucks and is negative given
* negative divisors.
* WARNING! This double- and triple- evaluates. */
#define POS_MOD(a, b) (((a) % (b) + (b)) % (b))
//helperClass //helperClass
class UtilityClass class UtilityClass
{ {