Adsp-2192 Dsp Rbtl And Overlays - Analog Devices VisualDSP++ 3.5 Manual

ADSP-2192 DSP Booting
The EZ-KIT Lite evaluation system driver can be reused for targets other
than Analog Devices EZ-KIT Lite evaluation systems, but this simple
driver may be inadequate for anything other than prototyping. Further-
more, the EZ-KIT Lite driver can be reused only on so-called
"plug-and-play" Windows operating systems like Windows 98 and Win-
dows 2000.

ADSP-2192 DSP RBTL and Overlays

Using overlays in an executable can greatly complicate the use of the
RTBL and PCI driver for two main reasons:
• The overlay's "live space" is on the PC host and not the DSP. As a
result, the linker is not aware of these addresses at build time. The
PCI driver must patch executables as they are downloaded to the
DSP to insert the correct addresses at runtime.
• The DSP cannot access the Windows virtual memory space. An
overlay must be copied from virtual memory space to PCI memory
space, which can only be allocated in limited quantities by the PCI
driver.
However, the loader output considers the need for run-time patches of the
executable. A portion of the data structure created by the loader is for the
express purpose of enabling user code in the RTBL to set up these
addresses at runtime. Refer to the reference RTBL for an example of how
this is done.
Due to the DSP's inability to access Windows virtual memory space, the
RTBL and driver must be coordinated to make overlays available in PCI
memory space. Typically, the overlay's image and size information is sent
to the driver. The driver
overlay and then copies the overlay to this space, thus making the overlay
available in the PCI memory space.
4-8
's a memory buffer equal in size to the
malloc()
VisualDSP++ Loader Manual
for 16-Bit Processors