Script for Laboratory: Designing embedded ASIPs - CES

nop
nop
...
; The r1 and r2 will be replaced by
; the used registers for those parameters. The r3 referrs
; to the register for the return value.
The asm directive to create inline assembly is CoSy specific and so it won’t compile e.g. with
gcc. To write a C-Code, that can be used with gcc and with CoSy and that also includes CoSy
specific inline assembly, one can use a “#ifdef COSY … #else … #endif” constructions
to handle a gcc-version and a CoSy-version in the same file. As explained in Chapter
8.3, a “#define COSY” directive is automatically added to the source code, if it is
compiled with the mkimg script. To use inline assembly with the CoSy compiled version and
an equivalent function call with the gcc-compiled version one can write something like:
#ifdef COSY
asm int example(int parameter1, int parameter2)
{
; ...
}
#else
int example(int parameter1, int parameter2)
{
// ...
}
#endif
The most important directives are explained in Figure 8-3. They concern restrictions to the
parameters and reservations of further registers.
Directive Explanation
.scratch
With this directive temporary registers can be requested. For example:
.scratch temp1, temp2
would reserve 2 registers which you can address in the assembly code as
@{temp1} and @{temp2}. For every scratch register you need a restrict
directive (see below). The name of a scratch register needs to be at least 2
characters long.
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