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Array Notation used in EDiSim

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• Array notation for signals in EDiSim
  • Fact:

    You can use array notation for signal names in EDiSim

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    Example:

    And circuit with array notation: Switch aa sw[0] '0' ZERO; Switch ba sw[1] '1' ONE; Switch ca sw[2] '1' ONE; And bb sw[0] sw[1] s[2] out; Probe bc out; Demo: /home/cs355001/bin/cs355sim /home/cs355001/demo/circuits/and.arr

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• Short-hand notation for a sequence of signals written in array notation
  • Short-hand notation for a series of signals that is written in array notation:

    In EDiSim, the notation: signalName[ a..b ] is the short-hand for: signalName[a] signalName[a+1] ... signalName[b] if b > a signalName[a] signalName[a-1] ... signalName[b] if b < a

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  • Example:

    Previously, we saw that we can use array notation to name a signal: Switch aa sw[0] '0' ZERO; Switch ba sw[1] '1' ONE; Switch ca sw[2] '1' ONE; And bb sw[0] sw[1] s[2] out; Probe bc out; Using the short-hand notation, we can replace sw[0] sw[1] s[2] with sw[0..2]: Switch aa sw[0] '0' ZERO; Switch ba sw[1] '1' ONE; Switch ca sw[2] '1' ONE; And bb sw[0..2] out; Probe bc out;

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  • Example Program: (Demo above code)                                                

    /home/cs355001/bin/cs355sim   /home/cs355001/demo/circuits/and.arr-notation

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• Defining macros using array-notation
  • Important fact:

    In many user-defined circuits, we use a series (sequence) of bits as a binary number

    Example: the FourBit_Adder user-defined component

    Define FourBit_Adder a3 a2 a1 a0 b3 b2 b1 b0 | CarryOut s3 s2 s1 s0; Full_Adder ch ZERO a0 b0 | c1 s0; Full_Adder cf c1 a1 b1 | c2 s1; Full_Adder cd c2 a2 b2 | c3 s2; Full_Adder cb c3 a3 b3 | CarryOut s3; Endef;

    Just imagine how clumsy the macro will become you had to write an adder circuit for a 32 bit number:

    Define Adder32 b31 b30 b29 b28 b27 b26 b25 b24 b23 b22 b21 b20 b19 b18 b17 b16 b15 b14 b13 b12 b11 b10 b9 b8 b7 b6 b5 b4 b3 b2 b1 b0 a31 a30 a29 a28 a27 a26 a25 a24 a23 a22 a21 a20 a19 a18 a17 a16 a15 a14 a13 a12 a11 a10 a9 a8 a7 a6 a5 a4 a3 a2 a1 a0 | s31 s30 s29 s28 s27 s26 s25 s24 s23 s22 s21 s20 s19 s18 s17 s16 s15 s14 s13 s12 s11 s10 s9 s8 s7 s6 s5 s4 s3 s2 s1 s0; ... Endef;

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    Solution:

    Define the macro using the short-hand notation for an array-notation for signals !!!

  • Example:

    The macro definition: Define FourBit_Adder a3 a2 a1 a0 b3 b2 b1 b0 | CarryOut s3 s2 s1 s0; Full_Adder ch ZERO a0 b0 | c1 s0; Full_Adder cf c1 a1 b1 | c2 s1; Full_Adder cd c2 a2 b2 | c3 s2; Full_Adder cb c3 a3 b3 | CarryOut s3; Endef; can be written as following using the short-hand notation for array notation: Define FourBit_Adder a[3..0] b[..0] | CarryOut s[3..0]; Full_Adder ch ZERO a[0] b[0] | c1 s[0]; Full_Adder cf c1 a[1] b[1] | c2 s[1]; Full_Adder cd c2 a[2] b[2] | c3 s[2]; Full_Adder cb c3 a[3] b[3] | CarryOut s[3]; Endef;

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  • Example Program: (Demo above code)                                                

    /home/cs355001/bin/cs355sim /home/cs355001/demo/circuits/4-bit-adder.arr

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• Important caveat when using array notation to define a macro
  • Important note:

    If you use array notation to define a macro, then: You must use the short-hand notation in the macro definition header         I.e.: you cannot use the invidual array elements as input/output parameters !!!

    Example: this format is illegal:

    Define FourBit_Adder a[3] a[2] a[1] a[0] b[3] b[2] b[1] b[0] | CarryOut s[3] s[2] s[1] s[0]; Full_Adder ch ZERO a[0] b[0] | c1 s[0]; Full_Adder cf c1 a[1] b[1] | c2 s[1]; Full_Adder cd c2 a[2] b[2] | c3 s[2]; Full_Adder cb c3 a[3] b[3] | CarryOut s[3]; Endef;