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1 .Chapter 9 TRAP Routines and Subroutines
8 .TRAP Mechanism Operation
9 .TRAP Routines and their Assembler Names
10 .Example: Using the TRAP Instruction
12 .9- 12 Example: Output Service Routine TRAP_PUTS ST R0,OS_SAVE_R0 ; save R0, R1, and R7 ST R1,OS_SAVE_R1 ST R7,OS_SAVE_R7 ADD R1,R0,#0 ; move string pointer (R0) into R1 TRAP_PUTS_LOOP LDR R0,R1,#0 ; write characters in string using OUT BRz TRAP_PUTS_DONE OUT ADD R1,R1,#1 BRnzp TRAP_PUTS_LOOP TRAP_PUTS_DONE LD R0,OS_SAVE_R0 ; restore R0, R1, and R7 LD R1,OS_SAVE_R1 LD R7,OS_SAVE_R7 RET stored in table, location x22
13 .9- 12 Example: Output Service Routine TRAP_PUTS ST R0,OS_SAVE_R0 ; save R0, R1, and R7 ST R1,OS_SAVE_R1 ST R7,OS_SAVE_R7 ADD R1,R0,#0 ; move string pointer (R0) into R1 TRAP_PUTS_LOOP LDR R0,R1,#0 ; write characters in string using OUT BRz TRAP_PUTS_DONE OUT ADD R1,R1,#1 BRnzp TRAP_PUTS_LOOP TRAP_PUTS_DONE LD R0,OS_SAVE_R0 ; restore R0, R1, and R7 LD R1,OS_SAVE_R1 LD R7,OS_SAVE_R7 RET stored in table, location x22
14 .9- 12 Example: Output Service Routine TRAP_PUTS ST R0,OS_SAVE_R0 ; save R0, R1, and R7 ST R1,OS_SAVE_R1 ST R7,OS_SAVE_R7 ADD R1,R0,#0 ; move string pointer (R0) into R1 TRAP_PUTS_LOOP LDR R0,R1,#0 ; write characters in string using OUT BRz TRAP_PUTS_DONE OUT ADD R1,R1,#1 BRnzp TRAP_PUTS_LOOP TRAP_PUTS_DONE LD R0,OS_SAVE_R0 ; restore R0, R1, and R7 LD R1,OS_SAVE_R1 LD R7,OS_SAVE_R7 RET stored in table, location x22
15 .9- 12 Example: Output Service Routine TRAP_PUTS ST R0,OS_SAVE_R0 ; save R0, R1, and R7 ST R1,OS_SAVE_R1 ST R7,OS_SAVE_R7 ADD R1,R0,#0 ; move string pointer (R0) into R1 TRAP_PUTS_LOOP LDR R0,R1,#0 ; write characters in string using OUT BRz TRAP_PUTS_DONE OUT ADD R1,R1,#1 BRnzp TRAP_PUTS_LOOP TRAP_PUTS_DONE LD R0,OS_SAVE_R0 ; restore R0, R1, and R7 LD R1,OS_SAVE_R1 LD R7,OS_SAVE_R7 RET stored in table, location x22
16 .9- 12 Example: Output Service Routine TRAP_PUTS ST R0,OS_SAVE_R0 ; save R0, R1, and R7 ST R1,OS_SAVE_R1 ST R7,OS_SAVE_R7 ADD R1,R0,#0 ; move string pointer (R0) into R1 TRAP_PUTS_LOOP LDR R0,R1,#0 ; write characters in string using OUT BRz TRAP_PUTS_DONE OUT ADD R1,R1,#1 BRnzp TRAP_PUTS_LOOP TRAP_PUTS_DONE LD R0,OS_SAVE_R0 ; restore R0, R1, and R7 LD R1,OS_SAVE_R1 LD R7,OS_SAVE_R7 RET stored in table, location x22
17 .9- 12 Example: Output Service Routine TRAP_PUTS ST R0,OS_SAVE_R0 ; save R0, R1, and R7 ST R1,OS_SAVE_R1 ST R7,OS_SAVE_R7 ADD R1,R0,#0 ; move string pointer (R0) into R1 TRAP_PUTS_LOOP LDR R0,R1,#0 ; write characters in string using OUT BRz TRAP_PUTS_DONE OUT ADD R1,R1,#1 BRnzp TRAP_PUTS_LOOP TRAP_PUTS_DONE LD R0,OS_SAVE_R0 ; restore R0, R1, and R7 LD R1,OS_SAVE_R1 LD R7,OS_SAVE_R7 RET stored in table, location x22
18 .9- 12 Example: Output Service Routine TRAP_PUTS ST R0,OS_SAVE_R0 ; save R0, R1, and R7 ST R1,OS_SAVE_R1 ST R7,OS_SAVE_R7 ADD R1,R0,#0 ; move string pointer (R0) into R1 TRAP_PUTS_LOOP LDR R0,R1,#0 ; write characters in string using OUT BRz TRAP_PUTS_DONE OUT ADD R1,R1,#1 BRnzp TRAP_PUTS_LOOP TRAP_PUTS_DONE LD R0,OS_SAVE_R0 ; restore R0, R1, and R7 LD R1,OS_SAVE_R1 LD R7,OS_SAVE_R7 RET stored in table, location x22
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