/sys$common/syshlp/helplib.hlb MACRO, VAX MACRO Assembler, Vector Instructions, VSUB  *Conan The Librarian (sorry for the slow response - running on an old VAX)

      Vector Floating Subtract

    Format:

      vector - vector:

       { VVSUBF }
       { VVSUBD }   [/U[0|1]]    Va, Vb, Vc
       { VVSUBG }
       {        }

      scalar - vector:

       { VSSUBF }
       { VSSUBD }   [/U[0|1]]    scalar, Vb, Vc
       { VSSUBG }
       {        }

    Architecture

    Format
    vector - vector:

       opcode   cntrl.rw

    scalar - vector (F_floating):

       opcode   cntrl.rw, min.rl

    scalar - vector (D_ and G_floating):

       opcode   cntrl.rw, min.rq
    opcodes

    8CFD    VVSUBF    Vector Vector Subtract F_floating

    8DFD    VSSUBF    Vector Scalar Subtract F_floating

    8EFD    VVSUBD    Vector Vector Subtract D_floating

    8FFD    VSSUBD    Vector Scalar Subtract D_floating

    8AFD    VVSUBG    Vector Vector Subtract G_floating

    8BFD    VSSUBG    Vector Scalar Subtract G_floating

    vector_control_word

             1 1 1 1 1
             5 4 3 2 1     8 7     4 3     0
            +-+-+-+-+-------+-------+-------+
            |M|M|E| |  Va   |       |       |
            |O|T|X|0|  or   |  Vb   |  Vc   |
            |E|F|C| |  0    |       |       |
            +-+-+-+-+-------+-------+-------+
    exceptions

       floating overflow
       floating reserved operand
       floating underflow

    operation
      FOR i <- 0 TO VLR-1
        IF {{MOE EQL 0} OR {{MOE EQL 1} AND {VMR<i> EQL MTF}}} THEN
          BEGIN
            IF VVSUBF THEN
               Vc[i]<31:0> <- Va[i]<31:0> - Vb[i]<31:0>
            IF VSSUBF THEN
               Vc[i]<31:0> <- min - Vb[i]<31:0>

            IF VVSUBD OR VVSUBG THEN
               Vc[i] <- Va[i] - Vb[i]
            IF VSSUBD OR VSSUBG THEN
               Vc[i] <- min - Vb[i]
          END