2.1. Using Provided HDL Templates 2.2. Instantiating IP Cores in HDL 2.3. Inferring Multipliers and DSP Functions 2.4. Inferring Memory Functions from HDL Code 2.5. Register and Latch Coding Guidelines 2.6. General Coding Guidelines 2.7. Designing with Low-Level Primitives 2.8. Recommended HDL Coding Styles Revision History
18.104.22.168. Use Synchronous Memory Blocks 22.214.171.124. Avoid Unsupported Reset and Control Conditions 126.96.36.199. Check Read-During-Write Behavior 188.8.131.52. Controlling RAM Inference and Implementation 184.108.40.206. Single-Clock Synchronous RAM with Old Data Read-During-Write Behavior 220.127.116.11. Single-Clock Synchronous RAM with New Data Read-During-Write Behavior 18.104.22.168. Simple Dual-Port, Dual-Clock Synchronous RAM 22.214.171.124. True Dual-Port Synchronous RAM 126.96.36.199. Mixed-Width Dual-Port RAM 188.8.131.52. RAM with Byte-Enable Signals 184.108.40.206. Specifying Initial Memory Contents at Power-Up
220.127.116.11. If Performance is Important, Optimize for Speed 18.104.22.168. Use Separate CRC Blocks Instead of Cascaded Stages 22.214.171.124. Use Separate CRC Blocks Instead of Allowing Blocks to Merge 126.96.36.199. Take Advantage of Latency if Available 188.8.131.52. Save Power by Disabling CRC Blocks When Not in Use 184.108.40.206. Initialize the Device with the Synchronous Load (sload) Signal
3.4.1. Apply Complete System-Centric Timing Constraints for the Timing Analyzer 3.4.2. Force the Identification of Synchronization Registers 3.4.3. Set the Synchronizer Data Toggle Rate 3.4.4. Optimize Metastability During Fitting 3.4.5. Increase the Length of Synchronizers to Protect and Optimize 3.4.6. Set Fitter Effort to Standard Fit instead of Auto Fit 3.4.7. Increase the Number of Stages Used in Synchronizers 3.4.8. Select a Faster Speed Grade Device
220.127.116.11. Use Separate CRC Blocks Instead of Allowing Blocks to Merge
Synthesis tools often attempt to optimize CRC designs by sharing resources and extracting duplicates in two different CRC blocks because of the factoring options in the XOR logic.
CRC logic allows significant reductions, but this works best when the Compiler optimizes CRC function separately. Check for duplicate extraction behavior if for designs with different CRC functions that are driven by common data signals or that feed the same destination signals.
For designs with poor quality results that have two CRC functions sharing logic you can ensure that the blocks are synthesized independently with one of the following methods:
- Define each CRC block as a separate design partition in an incremental compilation design flow.
- Synthesize each CRC block as a separate project in a third-party synthesis tool and then write a separate Verilog Quartus Mapping (.vqm) or EDIF netlist file for each.
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