From 373e1441d3f5db7ddd1cc919d8d1c9f447f3301e Mon Sep 17 00:00:00 2001
From: Brion Vibber <brion@pobox.com>
Date: Wed, 4 Jan 2023 21:09:45 -0800
Subject: [PATCH] comment tweaks

---
 mandel.s | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mandel.s b/mandel.s
index 46ad664..2b55f78 100644
--- a/mandel.s
+++ b/mandel.s
@@ -38,8 +38,8 @@ FRX = $ec
     .local next
 
     ; does 16-bit adds
-    ; arg1 must be 0 or positive
-    ; arg2 must be 0 or positive
+    ; arg1 and arg2 are treated as unsigned
+    ; negative signed inputs must be flipped first
 
     ; 7 cycles up to the branch
 
@@ -66,7 +66,7 @@ one: ; 32 cyc, 37 cyc
     sta result + 2 ; 3 cyc
     lda result + 3 ; 3 cyc
     adc arg2 + 1   ; 3 cyc
-    ror a          ; 2 cyc
+    ror a          ; 2 cyc - get a jump on the shift
     sta result + 3 ; 3 cyc
 next:
     ror result + 2 ; 5 cyc