RealView Compilation Tools Compiler Reference Guide - ARM ...

Compiler-specific Features
To use the indirect mechanism, your system handlers must make use of the r12 value to
select the required operation.
Usage
You can use this feature to implement indirect SVCs.
Example
int __svc_indirect(0) ioctl(int svcino, int fn, void *argp);
Calling:
ioctl(IOCTL+4, RESET, NULL);
compiles to SVC #0 with IOCTL+4 in r12.
Errors
When an ARM architecture variant or ARM architecture-based processor that does not
support an SVC instruction is specified on the command line using the --cpu option, the
compiler generates an error.
See also
• --cpu=name on page 2-15
• __value_in_regs on page 4-19
• SVC on page 4-130 in the Assembler Guide.
4.1.17 __svc_indirect_r7
The __svc_indirect keyword behaves like __svc_indirect, but uses r7 instead of r12.
__svcindirect_r7 is a function qualifier. It affects the type of a function.
Syntax
__svc_indirect_r7(int svc_num)
return-type function-name(int real_num[, argument-list]);
Where:
svc_num
Is the immediate value used in the SVC instruction.
It is an expression evaluating to an integer in the range:
• 0 to 2 24 –1 (a 24-bit value) in an ARM instruction
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