John Curreri

1
High Level Synthesis Overview

• John Curreri
• Seth Koehler

2
Outline

• Introduction
• High Level Synthesis
• Impulse C
• Computational parallelism
• Types of communication
• Communication Library
• Design Flow
• Tool demonstration

3
High Level Synthesis

• Translates C code to HDL
• Higher level of abstraction
• Usually a subset of ANSI C
• No pointers
• No ANSI C libraries for FPGA
• HDL is generated as a project file for Xilinx or
  Altera tools
• Built-in communication
• Separate C source files are made for the CPU
  FPGA
• Similar communication function calls between CPU
  FPGA

4
High Level Synthesis (continued)

• Computational parallelism
• Pipelining of loops
• for(), while(), etc.
• Use of library functions
• HDL coded functions called at HLL
• FFT, Floating point operations
• Replication of functions defined in hardware

• Types of communication
• DMA transfers
• Efficient transfer of large chucks of data
• Stream transfers
• Steady flow of data
• Buffered for transfer rate changes

5
Impulse C Communication Library

• Communication
• co_memory
• Large transfer size - DMA
• From CPU array to SRAM
• From SRAM to FPGA block RAM
• co_stream
• Small transfer size - FIFO buffered
• FIFO is implemented in block RAM on FPGA
• co_register
• Small transfer size - unbuffered
• Synchronization
• co_signal
• Single process to process
• One process waits for another to signal it to
  continue
• co_semaphore
• Multiple processes to processes

6
Design Flow
7
DEMO