__svc_indirect_r7 keyword behaves like
r7 instead of
__svc_indirect_r7 is a function qualifier.
It affects the type of a function.
svc_num) return-type function-name(int
Is the immediate value used in the
It is an expression evaluating to an integer in the range:
0 to 224-1 (a 24-bit value) in an ARM instruction
0-255 (an 8-bit value) in a 16-bit Thumb instruction.
Is the value passed in
r7to the handler to determine the function to perform.