HDD: Fixed SmartPort return address wrong when crossing page + some space-saving optimisations (Fixes #319)

firmware/HDD/hddrvr.a65

@@ -34,6 +34,7 @@
 ; . GH#370 (Robert Hoem, 27 Oct 2016):
 ;   . Added a check against open-apple during boot to route boot to slot 6
 ;   . This happens after the first two blocks are loaded from the HD.
+; . GH#319: smartport return address wrong when crossing page
 ; TODO:
 ; . Make code relocatable (so HDD controller card can go into any slot)
 ; . Remove support for Entrypoint_C746 (old AppleWin) & Entrypoint_C761 (Apple Oasis)
@@ -108,14 +109,7 @@ Bootstrap
 ; error capturing code.  Applewin is picky
 ; about code assigning data to registers and
 ; memory.  The safest method is via I/O port
- pha
- lda hd_error
- clc
- cmp #1
- bne noerr0
- sec
-noerr0
- pla
+ ror hd_error	; Post: C=0 or 1
  bcc hdboot
 
 ; no image ready, boot diskette image instead
@@ -129,12 +123,14 @@ BootSlot6
 SmartPort
  pla
  sta $46
+ adc #3         ; Pre: C=0, Post: C=0 or 1
+ tay
  pla
- sta $47		; ($47) = &cmd_hdr
+ sta $47        ; ($46) = &cmd_hdr
+ adc #0
  pha
- lda $46
- adc #3			; Pre: C=0, Post: assume C=0
- pha			; (sp).w += 3
+ tya
+ pha            ; (sp).w += 3
 
  ldy #1
  lda ($46),y	; cmd
@@ -143,7 +139,7 @@ SmartPort
  bne SmartPort2
 
 ;======================================
-; 2 unused bytes
+; 8 unused bytes
 
 *= $c746	; org $c746
 
@@ -237,12 +233,7 @@ cmdproc
  bne skipSread
  jsr sread
 skipSread
- lda hd_error
- clc
- cmp #1
- bne noerr2
- sec
-noerr2
+ ror hd_error	; Post: C=0 or 1
  pla
  rts
 
@@ -253,7 +244,7 @@ noerr2
 ; the emulated code increments the buffer by 1 on each read) to (memblock),y
 ; increment memblock+1 and read the second 256 bytes via hd_nextbyte.
 ;
-; if I could figure out how to consistantly get applewin to update it's memory regions all
+; if I could figure out how to consistently get applewin to update it's memory regions all
 ; this code can be moved into the emulation code (although, this is how I'd build the hardware
 ; anyway...)
 
@@ -299,7 +290,7 @@ SmartPort3
  bne cmdproc
 
 ;======================================
-; 12 unused bytes
+; 18 unused bytes
 
 !zone data