RealView Compilation Tools - ARM Information Center

Compiler-specific Features
Usage
This causes function invocations to be compiled inline as an AAPCS-compliant
operation that behaves similarly to a normal call to a function.
The __value_in_regs qualifier can be used to specify that a small structure of up to 16
bytes is returned in registers, rather than by the usual structure-passing mechanism
defined in the AAPCS.
Example
__svc(42) void terminate_1(int procnum); // terminate_1 returns no results
__svc(42) int terminate_2(int procnum); // terminate_2 returns one result
typedef struct res_type
{
int res_1;
int res_2;
int res_3;
int res_4;
} res_type;
__svc(42) __value_in_regs res_type terminate_3(int procnum);
// terminate_3 returns more than
// one result
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 2-30
• __value_in_regs on page 4-20
• SVC on page 4-133 in the Assembler Guide.
4.1.16 __svc_indirect
The __svc_indirect keyword passes an operation code to the SVC handler in r12.
__svc_indirect is a function qualifier. It affects the type of a function.
Syntax
__svc_indirect(int svc_num)
return-type function-name(int real_num[, argument-list]);
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