From 7b3de85a06e81d14ac0c73e8f9e1ab8e4a474beb Mon Sep 17 00:00:00 2001
From: Remy Oukaour <remy.oukaour@gmail.com>
Date: Tue, 16 Jan 2018 17:27:50 -0500
Subject: Avoid "+- 1" at every maskbits

---
 macros/code.asm | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

(limited to 'macros/code.asm')

diff --git a/macros/code.asm b/macros/code.asm
index 6e9c378e3..799c27d45 100644
--- a/macros/code.asm
+++ b/macros/code.asm
@@ -37,17 +37,17 @@ ENDM
 
 maskbits: MACRO
 ; masks just enough bits to cover the argument
-; e.g. "maskbits %00010100" becomes "and %00011111"
+; e.g. "maskbits 26" becomes "and %00011111" (since 26 - 1 = %00011001)
 ; example usage in rejection sampling:
 ; .loop
 ; 	call Random
-; 	maskbits 30 +- 1
+; 	maskbits 30
 ; 	cp 30
 ; 	jr nc, .loop
 x = 1
 rept 8
-if x < (\1)
-x = (x + 1) * 2 +- 1
+if x + 1 < (\1)
+x = x << 1 | 1
 endc
 endr
 	and x
-- 
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