From 81fb379a019dc2198156a7bfe967a64b52e07cde Mon Sep 17 00:00:00 2001
From: Bobbi Webber-Manners <bobbi.manners@gmail.com>
Date: Sat, 31 Jul 2021 20:19:15 -0400
Subject: [PATCH] Even more code cleanup!

---
 applecorn.po | Bin 143360 -> 143360 bytes
 applecorn.s  |   2 ++
 auxmem.s     |  26 +++-----------------------
 loader.s     |  17 ++++++++---------
 4 files changed, 13 insertions(+), 32 deletions(-)

diff --git a/applecorn.po b/applecorn.po
index eecf91bb023988093433c5a855131bb0bb7c7585..aad3a0f1b31e70fe7d2fba4ad8794aa3a007a846 100644
GIT binary patch
delta 3124
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diff --git a/applecorn.s b/applecorn.s
index 4e99194..f4db554 100644
--- a/applecorn.s
+++ b/applecorn.s
@@ -98,6 +98,8 @@ XFADDR      MAC
 * Macro to backup STRTL/STRTH then load XFADDR
 * Called by code running in aux mem
 XFADDRAUX   MAC
+            TSX
+            STX   $0101       ; Save alt SP
             PHA
             LDA   STRTL
             STA   STRTBCKL
diff --git a/auxmem.s b/auxmem.s
index e746293..937a68a 100644
--- a/auxmem.s
+++ b/auxmem.s
@@ -286,11 +286,6 @@ FINDHND     PHX
             STX   ZP1                        ; Points to filename
             STY   ZP1+1
 
-            TSX                              ; Stash alt ZP
-            STX   $0101
-
-            PLA
-            PHA
             CMP   #$00                       ; A=$00 = close
             BEQ   :CLOSE
 
@@ -311,8 +306,8 @@ FINDHND     PHX
             STA   $C004                      ; Write main
             STY   MOSFILE                    ; Length (Pascal string)
             STA   $C005                      ; Write aux
-            >>>   XFADDRAUX,OFILE
             PLA                              ; Recover options
+            >>>   XFADDRAUX,OFILE
 :S1         >>>   XFMAIN
 
 :CLOSE      STA   $C004                      ; Write main
@@ -353,8 +348,6 @@ BPUTHND     PHX
             STA   $C004                      ; Write to main memory
             STY   MOSFILE                    ; File reference number
             STA   $C005                      ; Write to aux memory
-            TSX                              ; Stash alt SP in $0101
-            STX   $0101
             >>>   XFADDRAUX,FILEPUT
             PLA                              ; Char to write
             PHA
@@ -373,8 +366,6 @@ BGETHND     PHX
             STA   $C004                      ; Write to main memory
             STY   MOSFILE                    ; File ref number
             STA   $C005                      ; Write to aux memory
-            TSX                              ; Stash alt SP in $0101
-            STX   $0101
             >>>   XFADDRAUX,FILEGET
             >>>   XFMAIN
 OSBGETRET
@@ -493,9 +484,6 @@ FILEHND     PHX
             STY   MOSFILE                    ; Length (Pascal string)
             STA   $C005                      ; Write aux
 
-            TSX
-            STX   $0101                      ; Store alt SP in $0101
-
             PLA                              ; Get action back
             PHA
             BEQ   :S1                        ; A=00 -> SAVE
@@ -1231,9 +1219,7 @@ STARHELP    LDA   #<:MSG
 STARQUIT    >>>   XFADDRAUX,QUIT
             >>>   XFMAIN
 
-STARCAT     TSX
-            STX   $0101                      ; Stash alt SP
-            >>>   XFADDRAUX,CATALOG
+STARCAT     >>>   XFADDRAUX,CATALOG
             >>>   XFMAIN
 STARCATRET
             >>>   ENTAUX
@@ -1241,9 +1227,7 @@ STARCATRET
 
 * Print one block of a catalog. Called by CATALOG
 * Block is in AUXBLK
-PRONEBLK    LDX   $0101                      ; Recover alt SP
-            TXS
-
+PRONEBLK    >>>   ENTAUX
             LDA   AUXBLK+4                   ; Get storage type
             AND   #$E0                       ; Mask 3 MSBs
             CMP   #$E0
@@ -1334,8 +1318,6 @@ STARDIR     LDA   ZP1                        ; Move ZP1->ZP3 (OSWRCH uses ZP1)
             STA   $C004                      ; Write main
             STX   MOSFILE                    ; Length byte
             STA   $C005                      ; Write aux
-            TSX
-            STX   $0101                      ; Stash alt SP
             >>>   XFADDRAUX,SETPFX
             >>>   XFMAIN
 STARDIRRET
@@ -1368,8 +1350,6 @@ CHKEOF      STA   $C004                      ; Write main mem
             STX   MOSFILE                    ; File reference number
             STA   $C005                      ; Write aux mem
             >>>   XFADDRAUX,FILEEOF
-            TSX                              ; Stash alt SP in $0101
-            STX   $0101
             >>>   XFMAIN
 CHKEOFRET
             >>>   ENTAUX
diff --git a/loader.s b/loader.s
index 064fe5e..cfa179f 100644
--- a/loader.s
+++ b/loader.s
@@ -3,6 +3,10 @@
 *
 * Applecorn loader code
 
+* Loads Acorn ROM file (16KB) from disk and writes it
+* to aux memory starting at $08000. Copies Applecorn MOS
+* to aux memory starting at AUXMOS1 and jumps to it.
+* (Note that the MOS code will relocate itself to $D000.)
 START       STZ   :BLOCKS
             LDX   #$00
 :L1         LDA   HELLO,X          ; Signon message
@@ -100,15 +104,10 @@ START       STZ   :BLOCKS
             EOR   #$A5             ; Checksum
             STA   RSTV+2
 
-            TSX
-            STX   $0100            ; Store SP at $0100
-            LDA   #<AUXMOS1        ; Start address in aux, for XFER
-            STA   STRTL
-            LDA   #>AUXMOS1
-            STA   STRTH
-            SEC                    ; Main -> Aux
-            BIT   $FF58            ; Set V; Use page zero and stack in aux
-            JMP   XFER             ; Jump to copied MOS code in Aux
+            TSX                    ; Save SP at $0100
+            STX   $0100
+            >>>   XFADDR,AUXMOS1
+            >>>   XFAUX
 
 :BLOCKS     DB    0                ; Counter for blocks read