From cc95d1208d4a6b8291a5430a8d652a9337074788 Mon Sep 17 00:00:00 2001
From: Remy Oukaour <remy.oukaour@gmail.com>
Date: Wed, 10 Jan 2018 11:57:28 -0500
Subject: Use maskbits more, and clarify its usage

---
 macros/code.asm | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

(limited to 'macros/code.asm')

diff --git a/macros/code.asm b/macros/code.asm
index 5ec214d50..5a0b82a24 100644
--- a/macros/code.asm
+++ b/macros/code.asm
@@ -39,15 +39,17 @@ ENDM
 mobile EQUS "ret"
 
 maskbits: MACRO
+; masks just enough bits to cover the argument
+; e.g. "maskbits %00010100" becomes "and %00011111"
 ; example usage in rejection sampling:
 ; .loop
 ; 	call Random
-; 	maskbits 30
+; 	maskbits 30 +- 1
 ; 	cp 30
 ; 	jr nc, .loop
 x = 1
 rept 8
-if \1 > x
+if x < (\1)
 x = (x + 1) * 2 +- 1
 endc
 endr
-- 
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