; loc_328:
ChecksumTest:
    ; optimized checksum routine by MarkeyJester
    if skipChecksumCheck=0  ; checksum code
    movea.l #EndOfHeader,a0 ; prepare start address
    move.l  (ROMEndLoc).w,d7    ; load size
    sub.l   a0,d7       ; minus start address
    move.b  d7,d5       ; copy end nybble
    andi.w  #$F,d5      ; get only the remaining nybble
    lsr.l   #4,d7       ; divide the size by 20
    move.w  d7,d6       ; load lower word size
    swap    d7      ; get upper word size
    moveq   #0,d0       ; clear d0
; loc_338:
.loop_main:
    add.w   (a0)+,d0    ; modular checksum (8 words)
    add.w   (a0)+,d0    ; ''
    add.w   (a0)+,d0    ; ''
    add.w   (a0)+,d0    ; ''
    add.w   (a0)+,d0    ; ''
    add.w   (a0)+,d0    ; ''
    add.w   (a0)+,d0    ; ''
    add.w   (a0)+,d0    ; ''
    dbf d6,.loop_main   ; repeat until all main block sections are done
    dbf d7,.loop_main   ; ''
    subq.w  #1,d5       ; decrease remaining nybble for dbf
    bpl.s   .done       ; if there is no remaining nybble, branch
.loop_extra:
    add.w   (a0)+,d0    ; add remaining words
    dbf d5,.loop_extra  ; repeat until the remaining words are done
.done:
    cmp.w   (Checksum).w,d0 ; compare correct checksum to the one in ROM
    bne.w   ChecksumError   ; if they don't match, branch
    endif