Datasheet

Chapter 10 XGATE (S12XGATEV3)
MC9S12XE-Family Reference Manual Rev. 1.25
466 Freescale Semiconductor
MOVW 2,X+, 2,Y+
MOVW 2,X+, 2,Y+
MOVW 2,X+, 2,Y+
CPX #XGATE_CODE_FLASH_END
BLS COPY_XGATE_CODE_LOOP
;###########################################
;# START XGATE #
;###########################################
START_XGATE MOVW #XGMCTL_ENABLE, XGMCTL ;enable XGATE
BRA *
;###########################################
;# DUMMY INTERRUPT SERVICE ROUTINE #
;###########################################
DUMMY_ISR RTI
CPU XGATE
;###########################################
;# XGATE DATA #
;###########################################
ALIGN 1
XGATE_DATA_FLASH EQU *
XGATE_DATA_SCI EQU *-XGATE_DATA_FLASH
DW SCI_REGS ;pointer to SCI register space
XGATE_DATA_IDX EQU *-XGATE_DATA_FLASH
DB XGATE_DATA_MSG ;string pointer
XGATE_DATA_MSG EQU *-XGATE_DATA_FLASH
FCC "Hello World! ;ASCII string
DB $0D ;CR
;###########################################
;# XGATE CODE #
;###########################################
ALIGN 1
XGATE_CODE_FLASH LDW R2,(R1,#XGATE_DATA_SCI) ;SCI -> R2
LDB R3,(R1,#XGATE_DATA_IDX) ;msg -> R3
LDB R4,(R1,R3+) ;curr. char -> R4
STB R3,(R1,#XGATE_DATA_IDX) ;R3 -> idx
LDB R0,(R2,#(SCISR1-SCI_REGS)) ;initiate SCI transmit
STB R4,(R2,#(SCIDRL-SCI_REGS)) ;initiate SCI transmit
CMPL R4,#$0D
BEQ XGATE_CODE_DONE
RTS
XGATE_CODE_DONE LDL R4,#$00 ;disable SCI interrupts
STB R4,(R2,#(SCICR2-SCI_REGS))
LDL R3,#XGATE_DATA_MSG;reset R3
STB R3,(R1,#XGATE_DATA_IDX)
XGATE_CODE_FLASH_END RTS
XGATE_DUMMY_ISR_XG EQU (XGATE_CODE_FLASH_END-XGATE_CODE_FLASH)+XGATE_CODE_XG
10.9.3 Stack Support
To simplify the implementation of a program stack the XGATE can be configured to set RISC core register
R7 to the beginning of a stack region before executing a thread. Two separate stack regions can be defined:
One for threads of priority level 7 to 4 (refer to Section 10.3.1.5, “XGATE Initial Stack Pointer for