From 4ae461b9332f5642df85b8c204d88601f6a1adef Mon Sep 17 00:00:00 2001
From: "B. Watson" <urchlay@slackware.uk>
Date: Wed, 8 Apr 2026 06:13:43 -0400
Subject: Commentary in jifsec.s

---
 src/jifsec.s | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

(limited to 'src')

diff --git a/src/jifsec.s b/src/jifsec.s
index 4972cdf..ca5aac7 100644
--- a/src/jifsec.s
+++ b/src/jifsec.s
@@ -28,14 +28,14 @@ _print_jif_sec:
 @printfrac:
  lda #'.' ; otherwise, we need a decimal point...
  jsr _scr_putc_active
- lda remainder
+ lda remainder ; remainder is 0..(_hz-1), scale to 100ths of a sec.
  ldx #0
- jsr mulax10
- jsr mulax10
+ jsr mulax10 ; convenient cc65 runtime routine...
+ jsr mulax10 ; AX now remainder * 100
  sta acc16
  stx acc16+1
- jsr divbyhz ; remainder /= hz
- lda acc16
+ jsr divbyhz ; acc16 = remainder / hz
+ lda acc16 ; acc16 range is 0..99 (ignore hi byte)
  cmp #$0a  ; does it need a leading zero?
  bcs @no_0
  lda #'0'
@@ -45,6 +45,11 @@ _print_jif_sec:
  ldx acc16+1
  jmp _scr_act_printnum ; print it, we're done
 
+; NOTE: if we wanted to, we could round, by checking the high bit
+; of remainder and adding one to acc16 before printing. not going
+; to bother for now, making it look more accurate won't make it
+; really *be* more accurate.
+
 ; divide 16-bit a/x by 8-bit _hz.
 ; result in acc16, remainder in remainder.
 divbyhz:
-- 
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