位宽不匹配(Width mismatch)

一、简介

SpinalHDL会检查赋值两侧的操作和信号有相同的位宽。

二、分配赋值例子

下述代码：

class TopLevel extends Component {
  val a = UInt(8 bits)
  val b = UInt(4 bits)
  b := a
}

将会报错：

WIDTH MISMATCH on (toplevel/b :  UInt[4 bits]) := (toplevel/a :  UInt[8 bits]) at
  ***
  Source file location of the OR operator via the stack trace
  ***

可以修复为：

class TopLevel extends Component {
  val a = UInt(8 bits)
  val b = UInt(4 bits)
  b := a.resized
}

三、操作实例

下述代码：

class TopLevel extends Component {
  val a = UInt(8 bits)
  val b = UInt(4 bits)
  val result = a | b
}

将会报错：

WIDTH MISMATCH on (UInt | UInt)[8 bits]
- Left  operand : (toplevel/a :  UInt[8 bits])
- Right operand : (toplevel/b :  UInt[4 bits])
  at
  ***
  Source file location of the OR operator via the stack trace
  ***

可修复为：

class TopLevel extends Component {
  val a = UInt(8 bits)
  val b = UInt(4 bits)
  val result = a | (b.resized)
}