clash-prelude-1.2.3: CAES Language for Synchronous Hardware - Prelude library
Copyright(C) 2015-2016 University of Twente
2019 Myrtle Software Ltd
2017 Google Inc.
LicenseBSD2 (see the file LICENSE)
MaintainerChristiaan Baaij <christiaan.baaij@gmail.com>
Safe HaskellUnsafe
LanguageHaskell2010
Extensions
  • MonoLocalBinds
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  • GADTs
  • GADTSyntax
  • DataKinds
  • InstanceSigs
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  • DeriveFunctor
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  • DeriveGeneric
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  • FlexibleContexts
  • MagicHash
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  • ExplicitForAll
  • BinaryLiterals
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Clash.Prelude.BlockRam.File

Description

Initializing a BlockRAM with a data file

BlockRAM primitives that can be initialized with a data file. The BNF grammar for this data file is simple:

FILE = LINE+
LINE = BIT+
BIT  = '0'
     | '1'

Consecutive LINEs correspond to consecutive memory addresses starting at 0. For example, a data file memory.bin containing the 9-bit unsigned number 7 to 13 looks like:

000000111
000001000
000001001
000001010
000001011
000001100
000001101

We can instantiate a BlockRAM using the content of the above file like so:

f :: HiddenClock dom  -> Signal dom (Unsigned 3) -> Signal dom (Unsigned 9)
f rd = unpack <$> exposeClock blockRamFile clk d7 "memory.bin" rd (pure Nothing)

In the example above, we basically treat the BlockRAM as an synchronous ROM. We can see that it works as expected:

>>> import qualified Data.List as L
>>> L.tail $ sampleN 4 $ f (fromList [3..5])
[10,11,12]

However, we can also interpret the same data as a tuple of a 6-bit unsigned number, and a 3-bit signed number:

g :: HiddenClock dom  -> Signal dom (Unsigned 3) -> Signal dom (Unsigned 6,Signed 3)
g clk rd = unpack <$> exposeClock blockRamFile clk d7 "memory.bin" rd (pure Nothing)

And then we would see:

>>> import qualified Data.List as L
>>> L.tail $ sampleN 4 $ g (fromList [3..5])
[(1,2),(1,3)(1,-4)]
Synopsis

BlockRAM synchronized to an arbitrary clock

blockRamFile Source #

Arguments

:: (KnownNat m, Enum addr, HiddenClock dom, HiddenEnable dom, HasCallStack) 
=> SNat n

Size of the blockRAM

-> FilePath

File describing the initial content of the blockRAM

-> Signal dom addr

Read address r

-> Signal dom (Maybe (addr, BitVector m))

(write address w, value to write)

-> Signal dom (BitVector m)

Value of the blockRAM at address r from the previous clock cycle

Create a blockRAM with space for n elements

  • NB: Read value is delayed by 1 cycle
  • NB: Initial output value is undefined
  • NB: This function might not work for specific combinations of code-generation backends and hardware targets. Please check the support table below:

                   | VHDL     | Verilog  | SystemVerilog |
    ===============+==========+==========+===============+
    Altera/Quartus | Broken   | Works    | Works         |
    Xilinx/ISE     | Works    | Works    | Works         |
    ASIC           | Untested | Untested | Untested      |
    ===============+==========+==========+===============+
    

Additional helpful information:

blockRamFilePow2 Source #

Arguments

:: forall dom n m. (KnownNat m, KnownNat n, HiddenClock dom, HiddenEnable dom, HasCallStack) 
=> FilePath

File describing the initial content of the blockRAM

-> Signal dom (Unsigned n)

Read address r

-> Signal dom (Maybe (Unsigned n, BitVector m))

(write address w, value to write)

-> Signal dom (BitVector m)

Value of the blockRAM at address r from the previous clock cycle

Create a blockRAM with space for 2^n elements

  • NB: Read value is delayed by 1 cycle
  • NB: Initial output value is undefined
  • NB: This function might not work for specific combinations of code-generation backends and hardware targets. Please check the support table below:

                   | VHDL     | Verilog  | SystemVerilog |
    ===============+==========+==========+===============+
    Altera/Quartus | Broken   | Works    | Works         |
    Xilinx/ISE     | Works    | Works    | Works         |
    ASIC           | Untested | Untested | Untested      |
    ===============+==========+==========+===============+
    

Additional helpful information: