Hello,
I'd like to change a VHDL shared variable's value from C code.
So far I can reuse the trick used for the framebuffer system
(see http://ygdes.com/GHDL/fb/fb_ghdl.vhdl :
package fb_ghdl is
...
type screen_type is
array(integer range 0 to fby1,
integer range 0 to fbxv1) of integer;
type screen_p is access screen_type;
-- alias :
function get_fbp(f : integer) return screen_p;
attribute foreign of get_fbp :
function is "VHPIDIRECT get_fb";
-- init the screen address
shared variable pixel : screen_p := get_fbp(0);
...
So with this system, I can sort-of alias a VHDL shared variable
to a C variable. This is for a dynamic flag that will be changed
by a POSIX signal for timing purposes.
the question is : how to do the reverse ?
What about getting the address of a GHDL variable
(in a package) and letting the C code change it ?
As far as I know : the only things that are transmitted
by address are arrays, but here I have a scalar.
I'd like to avoid having to objdump the compiled VHDL code
because I've only found confusing names, like
work__fb_ghdl__pixel and work__fb_ghdl__pixel__RTISTR
both as initialised and uninitialised data...
Is it safe to create the scalar, then a Access to it,
and provide the access to a C function ?
yg
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