From 32b92ca51c73f1ad9be169bef476b9c93687e2a4 Mon Sep 17 00:00:00 2001 From: Rangi Date: Wed, 23 May 2018 12:48:14 -0400 Subject: Start improving sprite movement engine (to do: identify bit flags) Introduce maskbits N[, S]: optionally shift the bitmask --- macros/code.asm | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'macros/code.asm') 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 -- cgit v1.2.3