Alazar API wrapper for Julia, bare-bones
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November 2015

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AlazarTech API wrapper for Julia, bare bones.

Adapted from the C and Python APIs by Andrew Keller (


using Alazar


This module provides a thin wrapper on top of the AlazarTech C API. Nearly all the exported methods directly map to underlying C functions. Please see the ATS-SDK Guide for detailed specification of these functions. It is up to the user to provide error handling.

alazaropen(), which loads the shared libraries, must be called once and only once after loading this package. When using multiple Julia worker processes, do not call it from workers or undefined behavior may occur. No manual cleanup is necessary upon exiting Julia.

Types introduced


    struct DMABufferVector{S,T} <: AbstractVector{S}

AlazarTech digitizers use direct memory access (DMA) to transfer data from digitizers to the computer's main memory. This struct abstracts memory buffers on the host. The elements of a DMABufferVector are pointers to the individual buffers, which are each page-aligned, since a page-aligned backing array is required (e.g. Base.SharedVector or Alazar.PageAlignedVector). In keeping with convention for AbstractVector{S}, we have eltype(::DMABufferVector{S}) = S. We also have S = Ptr{eltype(T)}.

DMABufferVector may be constructed as, for example, DMABufferVector(SharedVector{UInt8}, bytes_buf, n_buf) or DMABufferVector(Alazar.PageAlignedVector{UInt8}, bytes_buf, n_buf).

The fields of a DMABufferVector{S,T} are:

  • bytes_buf::Int: The number of bytes per buffer. If there is more than one buffer it should be a multiple of Base.Mmap.PAGESIZE. This is enforced in the inner constructor.
  • n_buf::Int: The number of buffers to allocate.
  • backing::T: The page-aligned backing array.

This code may not support 32-bit systems.


    mutable struct PageAlignedArray{T,N} <: AbstractArray{T,N}

An N-dimensional array of eltype T which is guaranteed to have its memory be page-aligned. This has to be a mutable struct because finalizers are used to clean up the memory allocated by C calls when there remain no references to the PageAlignedArray object in Julia.

Type aliases

  • PageAlignedVector{T} = PageAlignedArray{T,1}.

  • U32, U16, U8, S32, S16 are aliased to their respective unsigned and signed N-bit C types.

  • dsp_module_handle = Ptr{Void}.


  • Alazar8Bit, Alazar12Bit, Alazar16Bit. These encapsulate 8-bit, 12-bit, and 16-bit unsigned integers in the Alazar format. They have very little overhead being declared immutable, but have the advantage that 12-bit and 16-bit formats are distinguishable by type.


  • U16Log, U16Amp2, U8Log, U8Amp2, S32Real, S32Imag, FloatLog, FloatAmp2. Similar strategy as for AlazarBits types. Permits efficient encoding of FFT output data while distinguishing between e.g. S32Real and S32Imag.