loadMemoryFromFile

loadMemoryFromFile is an annotation generator that helps with loading a memory from a text file. This relies on Verilator and Verilog's $readmemh or $readmemb. The Treadle backend can also recognize this annotation and load memory at run-time.

This annotation, when the FIRRTL compiler runs, triggers the LoadMemoryTransform. That will add Verilog directives to enable the specified memories to be initialized from files.

Example module

Consider a simple Module containing a memory:

import chisel3._
class UsesMem(memoryDepth: Int, memoryType: Data) extends Module {
  val io = IO(new Bundle {
    val address = Input(UInt(memoryType.getWidth.W))
    val value   = Output(memoryType)
  })
  val memory = Mem(memoryDepth, memoryType)
  io.value := memory(io.address)
}

Above module with annotation

To load this memory from the file /workspace/workdir/mem1.hex.txt just add an import and annotate the memory:

import chisel3._
import chisel3.util.experimental.loadMemoryFromFile   // <<-- new import here
class UsesMem(memoryDepth: Int, memoryType: Data) extends Module {
  val io = IO(new Bundle {
    val address = Input(UInt(memoryType.getWidth.W))
    val value   = Output(memoryType)
  })
  val memory = Mem(memoryDepth, memoryType)
  io.value := memory(io.address)
  loadMemoryFromFile(memory, "/workspace/workdir/mem1.hex.txt")  // <<-- Note the annotation here
}

Example file format

A memory file should consist of ASCII text in either hex or binary format. The following example shows such a file formatted to use hex:

A binary file can be similarly constructed.

Source: LoadMemoryTransform.scala
See also: Chisel3 Wiki entry on "Loading Memories in Simulation"
LoadMemoryFromFileSpec.scala in the test suite for additional examples.

Linear Supertypes

AnyRef, Any

Value Members

final def !=(arg0: Any): Boolean

Definition Classes
AnyRef → Any
final def ##(): Int

Definition Classes
AnyRef → Any
final def ==(arg0: Any): Boolean

Definition Classes
AnyRef → Any
def apply[T <: Data](memory: MemBase[T], fileName: String, hexOrBinary: FileType = MemoryLoadFileType.Hex): Unit

Annotate a memory such that it can be initialized using a file
Annotate a memory such that it can be initialized using a file
memory
the memory
hexOrBinary
whether the file uses a hex or binary number representation
final def asInstanceOf[T0]: T0

Definition Classes
Any
def clone(): AnyRef

Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws( ... )
final def eq(arg0: AnyRef): Boolean

Definition Classes
AnyRef
def equals(arg0: Any): Boolean

Definition Classes
AnyRef → Any
def finalize(): Unit

Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws( classOf[java.lang.Throwable] )
final def getClass(): Class[_]

Definition Classes
AnyRef → Any
def hashCode(): Int

Definition Classes
AnyRef → Any
final def isInstanceOf[T0]: Boolean

Definition Classes
Any
final def ne(arg0: AnyRef): Boolean

Definition Classes
AnyRef
final def notify(): Unit

Definition Classes
AnyRef
final def notifyAll(): Unit

Definition Classes
AnyRef
final def synchronized[T0](arg0: ⇒ T0): T0

Definition Classes
AnyRef
def toString(): String

Definition Classes
AnyRef → Any
final def wait(): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )
final def wait(arg0: Long, arg1: Int): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )
final def wait(arg0: Long): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )

Related Doc: package experimental

object loadMemoryFromFile

Example module

Above module with annotation

Example file format

Value Members

final def !=(arg0: Any): Boolean

final def ##(): Int

final def ==(arg0: Any): Boolean

def apply[T <: Data](memory: MemBase[T], fileName: String, hexOrBinary: FileType = MemoryLoadFileType.Hex): Unit

final def asInstanceOf[T0]: T0

def clone(): AnyRef

final def eq(arg0: AnyRef): Boolean

def equals(arg0: Any): Boolean

def finalize(): Unit

final def getClass(): Class[_]

def hashCode(): Int

final def isInstanceOf[T0]: Boolean

final def ne(arg0: AnyRef): Boolean

final def notify(): Unit

final def notifyAll(): Unit

final def synchronized[T0](arg0: ⇒ T0): T0

def toString(): String

final def wait(): Unit

final def wait(arg0: Long, arg1: Int): Unit

final def wait(arg0: Long): Unit

Inherited from AnyRef

Inherited from Any

Ungrouped