# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1435499129 -7200
# Node ID c9cc853003d339d4fe204cc25b2f3366509de441
# Parent  caa80f526ae6b3df5d11538276a850677a3aaed5
Added user stack operations and updated the example tasks to maintain registers.

diff -r caa80f526ae6 -r c9cc853003d3 macros.oph
--- a/macros.oph	Sun Jun 28 14:08:35 2015 +0200
+++ b/macros.oph	Sun Jun 28 15:45:29 2015 +0200
@@ -183,4 +183,34 @@
     jmp copy_from_user_stack
 .macend
 
+; push A onto the "user space" stack
+;
+; affects: USER (gains A), TEMP
+
+.macro pushA
+    sei
+    pha
+    sty TEMP
+    ldy #0
+    sta (USER), y
+    .invoke sub16 1, USER
+    ldy TEMP
+    pla
+    cli
+.macend
+
+; pull A from the "user space" stack
+;
+; affects: A, USER (loses A), TEMP
+
+.macro pullA
+    sei
+    sty TEMP
+    .invoke add16 1, USER
+    ldy #0
+    lda (USER), y
+    ldy TEMP
+    cli
+.macend
+
 ; vim: tabstop=4 expandtab shiftwidth=4
diff -r caa80f526ae6 -r c9cc853003d3 switcher.oph
--- a/switcher.oph	Sun Jun 28 14:08:35 2015 +0200
+++ b/switcher.oph	Sun Jun 28 15:45:29 2015 +0200
@@ -26,6 +26,8 @@
 .alias CURRENT $74
 .alias CURRENTH $75
 .alias USER $76
+.alias USERH $77
+.alias TEMP $78
 .alias ARG0 $80
 .alias ARG0H $81
 .alias ARG1 $82
@@ -407,8 +409,11 @@
     .byte 0 ; saved flags
     .word first_task_start ; saved PC
 first_task_start:
-    .invoke add16 1, $7000
-    jmp first_task_start
+    lda #1
+first_task_continue:
+    sta $7000
+    adc #1
+    jmp first_task_continue
 
 
 
@@ -418,8 +423,11 @@
     .byte 0 ; saved flags
     .word second_task_start ; saved PC
 second_task_start:
-    .invoke add16 1, $7008
-    jmp second_task_start
+    lda #1
+second_task_continue:
+    sta $7008
+    adc #1
+    jmp second_task_continue
 
 
 
@@ -429,20 +437,25 @@
     .byte 0 ; saved flags
     .word third_task_start ; saved PC
 third_task_start:
-    .invoke store16 0, $7010
     ldx #0
+    ldy #0
 _loop:
-    lda $7010
-    cmp #$ff
+    cpy #$ff
     bne _continue
+    inc $7011
     lda $7011
     cmp #$ff
     bne _continue
+    tya
+    .invoke pushA
     txa
     .invoke call remove_task
+    .invoke pullA
+    tay
     inx
 _continue:
-    .invoke add16 1, $7010
+    iny
+    sty $7010
     jmp _loop
 third_task_stack:
     .word 0