From a6a91349bcf7225995a56fb3e84865277f1abebd Mon Sep 17 00:00:00 2001
From: rumbledethumps <16963588+rumbledethumps@users.noreply.github.com>
Date: Tue, 2 Dec 2025 21:37:14 -0800
Subject: [PATCH] make time zone work

---
 include/time.h             |  9 ++++++---
 libsrc/common/localtime.s  | 36 ++++++++++++++++++++++++++----------
 libsrc/common/tzset_time.s | 16 ++++++++++++++++
 libsrc/rp6502/ria_tzset.c  |  9 ---------
 libsrc/rp6502/tzset_time.s | 29 +++++++++++++++++++++++++++++
 5 files changed, 77 insertions(+), 22 deletions(-)
 create mode 100644 libsrc/common/tzset_time.s
 delete mode 100644 libsrc/rp6502/ria_tzset.c
 create mode 100644 libsrc/rp6502/tzset_time.s

diff --git a/include/time.h b/include/time.h
index 5eb6f144a..3fab28454 100644
--- a/include/time.h
+++ b/include/time.h
@@ -128,12 +128,15 @@ extern struct _timezone {
     char    dstname[5]; /* Name when daylight true, e.g. CEST */
 } _tz;
 
+/* Set _tz for a specific time, if supported by target */
+void __fastcall__ tzset_time (time_t* t);
+
 #define CLK_TCK                 CLOCKS_PER_SEC
 
 /* POSIX function prototypes */
-int __fastcall__ clock_getres (clockid_t clock_id, struct timespec *res);
-int __fastcall__ clock_gettime (clockid_t clock_id, struct timespec *tp);
-int __fastcall__ clock_settime (clockid_t clock_id, const struct timespec *tp);
+int __fastcall__ clock_getres (clockid_t clock_id, struct timespec* res);
+int __fastcall__ clock_gettime (clockid_t clock_id, struct timespec* tp);
+int __fastcall__ clock_settime (clockid_t clock_id, const struct timespec* tp);
 
 #endif
 
diff --git a/libsrc/common/localtime.s b/libsrc/common/localtime.s
index 279442c9d..bc64a19cd 100644
--- a/libsrc/common/localtime.s
+++ b/libsrc/common/localtime.s
@@ -5,16 +5,27 @@
 ;
 
         .export         _localtime
-        .import         __time_t_to_tm, __tz
+        .import         __time_t_to_tm, __tz, _tzset_time
         .import         ldeaxi, tosaddeax, pusheax
-        .importzp       sreg
+        .importzp       sreg, ptr1
 
 _localtime:
-        cpx     #$00            ; Check for null pointer
-        bne     :+
-        cmp     #$00
-        beq     no_pointer
-:       jsr     ldeaxi          ; Load value
+.if .cap(CPU_HAS_PUSHXY)
+        pha
+        phx
+        jsr     _tzset_time
+        plx
+        pla
+.else
+        pha
+        txa
+        pha
+        jsr     _tzset_time
+        pla
+        tax
+        pla
+.endif
+        jsr     ldeaxi          ; Load value
         jsr     pusheax         ; Push it
         lda     __tz+1+3
         sta     sreg+1
@@ -23,7 +34,12 @@ _localtime:
         ldx     __tz+1+1
         lda     __tz+1
         jsr     tosaddeax       ; Add _tz.timezone
-       jmp     __time_t_to_tm   ; Convert to struct tm
-
-no_pointer:
+        jsr     __time_t_to_tm  ; Convert to struct tm
+        sta     ptr1            ; Save returned tm pointer
+        stx     ptr1+1
+        ldy     #16
+        lda     __tz+0          ; Load _tz.daylight
+        sta     (ptr1),y        ; Store to tm.tm_isdst
+        lda     ptr1            ; Restore returned tm pointer
+        ldx     ptr1+1
         rts                     ; A/X already set
diff --git a/libsrc/common/tzset_time.s b/libsrc/common/tzset_time.s
new file mode 100644
index 000000000..5c0160404
--- /dev/null
+++ b/libsrc/common/tzset_time.s
@@ -0,0 +1,16 @@
+; tzset_time.s
+;
+; This file is part of
+; cc65 - a freeware C compiler for 6502 based systems
+;
+; https://cc65.github.io
+;
+; See "LICENSE" file for legal information.
+;
+; void __fastcall__ tzset_time (time_t* time);
+;
+
+        .export         _tzset_time
+
+_tzset_time:
+        rts
diff --git a/libsrc/rp6502/ria_tzset.c b/libsrc/rp6502/ria_tzset.c
deleted file mode 100644
index 3f39e44f2..000000000
--- a/libsrc/rp6502/ria_tzset.c
+++ /dev/null
@@ -1,9 +0,0 @@
-#include <rp6502.h>
-#include <time.h>
-
-int clock_gettimezone (time_t time, clockid_t clock_id, struct _timezone* tz);
-
-void ria_tzset (unsigned long time)
-{
-    clock_gettimezone (time, CLOCK_REALTIME, &_tz);
-}
diff --git a/libsrc/rp6502/tzset_time.s b/libsrc/rp6502/tzset_time.s
new file mode 100644
index 000000000..60c1177d7
--- /dev/null
+++ b/libsrc/rp6502/tzset_time.s
@@ -0,0 +1,29 @@
+; tzset_time.s
+;
+; This file is part of
+; cc65 - a freeware C compiler for 6502 based systems
+;
+; https://cc65.github.io
+;
+; See "LICENSE" file for legal information.
+;
+; void __fastcall__ tzset_time (time_t* time);
+;
+
+        .export         _tzset_time
+        .import         _clock_gettimezone, __tz
+        .import         pushax, ldax0sp, ldeaxi, pusheax, pusha, incsp2
+        .include        "time.inc"
+
+
+_tzset_time:
+        jsr     pushax
+        jsr     ldax0sp
+        jsr     ldeaxi
+        jsr     pusheax
+        lda     #CLOCK_REALTIME
+        jsr     pusha
+        lda     #<(__tz)
+        ldx     #>(__tz)
+        jsr     _clock_gettimezone
+        jmp     incsp2