AndesCore supports both software overlay and hardware overlay. For hardware overlay, please refer
http://forum.andestech.com/viewtopic.php?f=16&t=861&view=previous to get sample code, it needs OSC IP. For software overlay, the original sample code can be get from:
http://forum.andestech.com/viewtopic.php?f=25&t=827&view=previous. Now we refine the sample code to support all AndesCores and all Andes platforms, it is based on demo-printf and also ways to run is same.
As the demo code is configured to run on N968A + AG101P FPGA with XIP Mode. the sag file "nds32-xip.sag" is:
Attachment:
sag.png [ 27.7 KiB | Viewed 18635 times ]
Please note that Andes SAG tool specifies each function's VMA & LMA to a table "_ovly_table":
Code:
.nds32.ovly.tbl : AT(LOADADDR (.dynamic) + SIZEOF (.dynamic))
{
_ovly_table = .;
LONG(ABSOLUTE(ADDR(.overlay0)));
LONG(SIZEOF(.overlay0));
LONG(ABSOLUTE(LOADADDR(.overlay0)));
LONG(0);
LONG(ABSOLUTE(ADDR(.overlay1)));
LONG(SIZEOF(.overlay1));
LONG(ABSOLUTE(LOADADDR(.overlay1)));
LONG(0);
LONG(ABSOLUTE(ADDR(.overlay2)));
LONG(SIZEOF(.overlay2));
LONG(ABSOLUTE(LOADADDR(.overlay2)));
LONG(0);
LONG(ABSOLUTE(ADDR(.overlay3)));
LONG(SIZEOF(.overlay3));
LONG(ABSOLUTE(LOADADDR(.overlay3)));
LONG(0);
LONG(ABSOLUTE(ADDR(.overlay4)));
LONG(SIZEOF(.overlay4));
LONG(ABSOLUTE(LOADADDR(.overlay4)));
LONG(0);
LONG(ABSOLUTE(ADDR(.overlay5)));
LONG(SIZEOF(.overlay5));
LONG(ABSOLUTE(LOADADDR(.overlay5)));
LONG(0);
_novlys = .;
LONG((_novlys - _ovly_table) / 16);
. = ALIGN(8);
}
In ovlymgr.c, define the external table:
Code:
extern unsigned long _ovly_table[][4];
Please also note that every time you want to run overlay function, please call our API to load the function (from LMA to VMA). The demo code is:
Code:
void
overlay ()
{
puts("/* Enter overlay Root portion */\n\r");
OverlayLoad (0);
OverlayLoad (4);
overlay0 ();
OverlayLoad (1);
overlay1 ();
OverlayLoad (2);
OverlayLoad (5);
overlay2 ();
OverlayLoad (3);
overlay3 ();
return;
}
We get technical article to show the principle of software overlay :
http://image.edntaiwan.com/140110_Tech_Paper_from_Andes.pdfAttachment:
demo-printf-overlay.zip [305.25 KiB]
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