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| author | Sven Eisenhauer <sven@sven-eisenhauer.net> | 2023-11-10 15:11:48 +0100 |
|---|---|---|
| committer | Sven Eisenhauer <sven@sven-eisenhauer.net> | 2023-11-10 15:11:48 +0100 |
| commit | 33613a85afc4b1481367fbe92a17ee59c240250b (patch) | |
| tree | 670b842326116b376b505ec2263878912fca97e2 /Bachelor/Mikroprozessorsysteme2/ARM202U/EXAMPLES/SWI/HANDLE.S | |
| download | Studium-master.tar.gz Studium-master.tar.bz2 | |
Diffstat (limited to 'Bachelor/Mikroprozessorsysteme2/ARM202U/EXAMPLES/SWI/HANDLE.S')
| -rw-r--r-- | Bachelor/Mikroprozessorsysteme2/ARM202U/EXAMPLES/SWI/HANDLE.S | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/Bachelor/Mikroprozessorsysteme2/ARM202U/EXAMPLES/SWI/HANDLE.S b/Bachelor/Mikroprozessorsysteme2/ARM202U/EXAMPLES/SWI/HANDLE.S new file mode 100644 index 0000000..6056035 --- /dev/null +++ b/Bachelor/Mikroprozessorsysteme2/ARM202U/EXAMPLES/SWI/HANDLE.S @@ -0,0 +1,42 @@ + AREA TopSwiHandler, CODE ; name this block of code
+
+ EXPORT SWIHandler
+ EXPORT MakeChain
+ IMPORT C_SWI_Handler
+ IMPORT Dswivec
+SWIHandler
+ SUB r13, r13, #4 ; leave space to store spsr
+ STMFD r13!, {r0-r12,r14} ; store registers
+ MOV r1, r13 ; second parameter to C routine
+ ; is register values.
+ LDR r0,[r14,#-4] ; Calculate address of SWI instruction
+ ; and load it into r0
+ BIC r0,r0,#0xff000000 ; mask off top 8 bits of instruction
+ MRS r2, spsr
+ STR r2,[r13,#14*4] ; store spsr on stack at original r13
+ BL C_SWI_Handler ; Call C routine to handle SWI
+ CMP r0, #0 ; Has C routine handled SWI ?
+ ; 0 = no, 1 = yes
+ LDR r2, [r13,#14*4] ; extract spsr from stack
+ MSR spsr,r2 ; and restore it
+ LDMFD r13!, {r0-r12,lr} ; Restore original registers
+ ADD r13,r13,#4
+ ; Now need to decide whether to return from handler or to call
+ ; the next handler in the chain (the debugger's).
+ MOVNES pc,lr ; return from handler if SWI handled
+ LDR pc, swichain ; else jump to address containing
+ ; instruction to branch to address of
+ ; debugger's SWI handler.
+
+swichain
+ DCD 0
+
+MakeChain
+ LDR r0, =swichain
+ LDR r1, =Dswivec
+ LDR r2, [r1]
+ STR r2, [r0]
+ MOV pc,lr
+
+ END ; mark end of this file
+
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