diff options
| author | Rangi <remy.oukaour+rangi42@gmail.com> | 2018-05-23 12:48:14 -0400 |
|---|---|---|
| committer | Rangi <remy.oukaour+rangi42@gmail.com> | 2018-05-23 12:48:14 -0400 |
| commit | 32b92ca51c73f1ad9be169bef476b9c93687e2a4 (patch) | |
| tree | 310cbf0ee30c832941a1afc0da5ff35e1089c292 /macros/code.asm | |
| parent | 4e776d4fa6bb0510fa06416ad7a6dd9ffe0ff724 (diff) | |
Start improving sprite movement engine (to do: identify bit flags)
Introduce maskbits N[, S]: optionally shift the bitmask
Diffstat (limited to 'macros/code.asm')
| -rw-r--r-- | macros/code.asm | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/macros/code.asm b/macros/code.asm index 1fb651f30..09b15255e 100644 --- a/macros/code.asm +++ b/macros/code.asm @@ -36,8 +36,10 @@ jumptable: MACRO ENDM maskbits: MACRO -; masks just enough bits to cover the argument +; masks just enough bits to cover the first argument +; the second argument is an optional shift amount ; e.g. "maskbits 26" becomes "and %00011111" (since 26 - 1 = %00011001) +; and "maskbits 3, 2" becomes "and %00001100" (since "maskbits 3" becomes %00000011) ; example usage in rejection sampling: ; .loop ; call Random @@ -50,7 +52,11 @@ if x + 1 < (\1) x = x << 1 | 1 endc endr +if _NARG == 2 + and x << (\2) +else and x +endc ENDM calc_sine_wave: MACRO |