Motorola MSC8101 ADS User's Guide Page 312

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C-4 MSC8101 User’s Guide
Bootloader Program
;; calculating the checksum
; during the loading process the check sum is calculated for the whole
; long and at the end of the block the two words in the calculated
; checksum are xored with each other to get the real checksum
Fmain
move.l emr,d1
extractu #3,#19,d1,d3
; d3 xor 3’b100 to recover original isb
eor #$4,d3.l
nop
jmp find_siubase
return_find_siu
; SRAM INIT
jmp sram_init
return_sram_init
; initialize ELIRE
move.w #$8000,d0
nop
move.w d0,ELIRE
; initialize ELIRF
move.w #$0008,d0
nop
move.w d0,ELIRF
;;check the scmr to see which upm routine to load
move.l (r6+$c88),d1 ;;scmr,d1
;; extract the busdf from scmr
extractu #4,#20,d1,d3
jmp upmc_init
check_boot
move.l emr,d1
;get EE4,EE5 -> d3
extractu #2,#17,d1,d3
nop ;
cmpeq.w #$0,d3
jt external_memory
cmpeq.w #$1,d3
jt from_host
;if the value of [EE4,EE5] is not 00 or 01 stop
stop
external_memory
;d3 <- isb[0,1,2]
extractu #3,#19,d1,d3
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