# Tilegrid Fuzzer
This fuzzer creates the tilegrid.json bitstream database. This database contains segment definitions including base frame address and frame offsets.
## Example workflow for CLB generate.tcl LOCs one LUT per segment column towards generating frame base addresses.
A reference bitstream is generated and then: - a series of bitstreams are generated each with one LUT bit toggled; then - these are compared to find a toggled bit in the CLB segment column; then - the resulting address is truncated to get the base frame address.
Finally, generate.py calculates the segment word offsets based on known segment column structure
## Environment variables
### XRAY_ROI This environment variable must be set with a valid ROI. See database for example values
### XRAY_EXCLUDE_ROI_TILEGRID This environment variable must be set in case the part selected does not allow some tiles to be locked.
Error example (when using the artix 200T part): ERROR: [Place 30-25] Component carry4_SLICE_X82Y249 has been locked to a prohibited site SLICE_X82Y249.
To avoid this error, the XRAY_EXCLUDE_ROI_TILEGRID defines an ROI that is not taken into account when building the tilegrid, therefore excluding the problematic un-lockable sites.
As the resulting output file, tilegrid.json, is going to be checked against the one produced in the 074-dump_all fuzzer, also the latter one needs to produce a reduced tilegrid, with the excluded tiles specified with the environment variable.
### XRAY_ROI_FRAMES This can be set to a specific value to speed up processing and reduce disk space If you don’t know where your ROI is, just set to to include all values (0x00000000:0xfffffff)
### XRAY_ROI_GRID_* Optionally, use these as a small performance optimization: - XRAY_ROI_GRID_X1 - XRAY_ROI_GRID_X2 - XRAY_ROI_GRID_Y1 - XRAY_ROI_GRID_Y2
These should, if unused, be set to -1, with this caveat:
WARNING: CLB test generates this based on CLBs but implicitly includes INT
Therefore, if you don’t set an explicit XRAY_ROI_GRID_* it may fail if you don’t have a CLB*_L at left and a CLB*_R at right.