From 7e4f067c350c39cbb51a90ec8f9be851f3019315 Mon Sep 17 00:00:00 2001
From: Stephen Heumann <stephenheumann@gmail.com>
Date: Sat, 31 Dec 2022 19:10:36 -0600
Subject: [PATCH] Compute tm_yday and tm_wday directly in ~gmlocaltime.

This avoids calling mktime (future versions of which may call ~gmlocaltime), and also deals correctly with time zones.
---
 time.asm    | 28 ++++++++++++++++++++++++++--
 time.macros | 12 ++++++++++++
 2 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/time.asm b/time.asm
index 00aeea8..5cc9ff6 100644
--- a/time.asm
+++ b/time.asm
@@ -588,6 +588,7 @@ lb2b     dec   month
          lda   month                    set the month
          ldy   #tm_mon
          sta   [tm],y
+         ph4   <t                       save original t value
          sub4  t,count                  find the number of seconds
          move4 t,t1
          div4  t,#60
@@ -614,8 +615,31 @@ lb2b     dec   month
          inc   A
          ldy   #tm_mday
          sta   [tm],y
-         ph4   tm                       set the day of week/year
-         jsl   mktime
+         pl4   t                        restore original t value
+         stz   month                    compute the days since the start of the
+         jsr   factor_second32           year (in desired time zone)
+         sub4  t,count,count
+         div4  count,#60*60*24
+         ldy   #tm_yday                 set the day of year
+         lda   count
+         sta   [tm],y
+lb3      cmpl  t,#7*3000*60*60*24       compute the day of week
+         blt   lb3a
+         sub4  t,#7*3000*60*60*24
+         bra   lb3
+lb3a     add4  t,#4*60*60*24
+         sec                            (adjust for time zone)
+         lda   t
+         sbc   tz_offset
+         sta   t
+         lda   t+2
+         sbc   tz_offset+2
+         sta   t+2
+         div4  t,#60*60*24
+         mod4  t,#7 
+         lda   t                        set the day of week
+         ldy   #tm_wday
+         sta   [tm],y
          lda   isdst                    set the DST flag
          ldy   #tm_isdst
          sta   [tm],y
diff --git a/time.macros b/time.macros
index f65e0b5..b91948e 100644
--- a/time.macros
+++ b/time.macros
@@ -655,3 +655,15 @@
  sta &n1+6
  ~restm
  mend
+ macro
+&l cmpl &n1,&n2
+ lclb &yistwo
+&l ~setm
+ ~lda.h &n1
+ ~op.h cmp,&n2
+ bne ~a&SYSCNT
+ ~lda &n1
+ ~op cmp,&n2
+~a&SYSCNT anop
+ ~restm
+ mend