From 705f19cae38eb3e6a7e434979ec7a89dc8a1c732 Mon Sep 17 00:00:00 2001
From: "B. Watson" <urchlay@slackware.uk>
Date: Mon, 28 Apr 2025 22:13:27 -0400
Subject: reloc.s: commentary, remove verbose_memlo_check.

---
 reloc.s | 45 ++++++++-------------------------------------
 1 file changed, 8 insertions(+), 37 deletions(-)

diff --git a/reloc.s b/reloc.s
index 857be8f..ed22f13 100644
--- a/reloc.s
+++ b/reloc.s
@@ -1,15 +1,9 @@
 ;;; reloc.s - relocate code. this is just one puzzle piece.
 ;;; see README.txt for details.
 
-; uncomment to enable user-friendly "MEMLO is too high" error.
-; adds ~80 bytes to the code size. also, makes reloc.xex non-relocatable.
-; currently not a problem, but may be in the future.
- ;verbose_memlo_check = 1
-
  .export _main
  .include "atari.inc"
 
- ;start_addr = $6c00
  start_addr = $71c0
 
  ; mkrelocxex.c appends this stuff.
@@ -19,6 +13,7 @@
  code_init  = end_addr+6
  table      = end_addr+8
 
+ ; we use 9 bytes of zero page, in the floating-point area.
  zp_addr      = FR0
  offset_pages = zp_addr   ; 1 byte
  table_ptr    = zp_addr+1 ; 2 bytes
@@ -27,6 +22,7 @@
  shfreg       = zp_addr+7 ; 1 byte
  pagecount    = zp_addr+8 ; 1 byte
 
+ ; "manually" create the atari binary load header.
  .org start_addr - 6
  .word $ffff
  .word start_addr
@@ -49,32 +45,9 @@ calc_offset:
 
  bcs relocate_code
 
- .ifdef verbose_memlo_check
- ; whoops, MEMLO is too high, print message and wait for keystroke
 whoops:
- ldx #0
- lda #<whoops_msg
- sta ICBAL
- lda #>whoops_msg
- sta ICBAL+1
- lda #whoops_len
- sta ICBLL
- stx ICBLH
- lda #PUTCHR
- sta ICCOM
- jsr CIOV
-exitwait:
- lda CH
- cmp #$ff
- beq exitwait
- lda #$ff
- sta CH
- lda #0
- sta COLOR2
- rts
- .else
+ ; whoops, MEMLO is too high!
 freeze: bcc freeze ; wait for the user to press Reset.
- .endif
 
 relocate_code:
  ; adjust addresses while moving the code.
@@ -134,17 +107,20 @@ shiftit:
  inx
  lda (code_ptr),y
  asl shfreg
- bcc dontadj
+ bcc store_byte
  sbc offset_pages
 
-dontadj:
+store_byte:
+ ; store the (possibly adjusted) byte at the destination...
  sta (dest_ptr),y
+
  iny
  bne move_loop
  inc code_ptr+1
  inc dest_ptr+1
  dec pagecount
  bne move_loop
+ ;;; end of relocate_code
 
  ; bump MEMLO to point one byte past the end of the moved code.
  lda code_end
@@ -188,11 +164,6 @@ do_init:
 done:
  rts
 
- .ifdef verbose_memlo_check
-whoops_msg: .byte "MEMLO is too high! Press any key to exit.", EOL
- whoops_len = (*-whoops_msg)
- .endif
-
 end_addr:
 
  .out .sprintf("reloc.s code size $%04x (%d)", (* - start_addr), (* - start_addr))
-- 
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