cc_lerp_booth0.v
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////////////////////////////////////////////////////////////////////////
//
// Project Reality
//
// module: cc_lerp_booth0
// description: Pseudo-Booth encoder for lerp for color combine unit.
// Generates 1 10 bit partial product. This does 7 partials
// for lerp subtract/multiply. This effectively does the
// subtract without propagating the carries. The negative
// input is first 1's complemented, then the two inputs are
// considered bitwise. If none is set, mask out the multiply
// input. If one bit is set, pass the mpy input as a partial
// product. If both bits are set, shift up one bit.
// This implements the "Akeley" interpretation of the
// subtract inputs. The 9 bit inputs treated as unsigned if
// the 2 msb's are 10, else are sign extended before
// the subtract, and all 10 bits of result are used in the
// multiply by the other 9 bit input.
//
// designer: Phil Gossett
// date: 6/25/94
//
////////////////////////////////////////////////////////////////////////
module cc_lerp_booth0 (x, y, a, p);
input x;
input y;
input [8:0] a;
wire [9:0] pp;
output [9:0] p; // pseudo-booth encoded partial product
fn05d2 mux0s0 (.zn(msel), .a1(x), .b1(y)); // msel = x && !y
fn01d2 mux0e0 (.zn(menb), .a1(x), .b1(y)); // menb = x || !y
mx21d1h mux0b0 (.s(msel), .i0(a[0]), .i1(1'b0), .z(pp[0]));
mx21d1h mux0b1 (.s(msel), .i0(a[1]), .i1(a[0]), .z(pp[1]));
mx21d1h mux0b2 (.s(msel), .i0(a[2]), .i1(a[1]), .z(pp[2]));
mx21d1h mux0b3 (.s(msel), .i0(a[3]), .i1(a[2]), .z(pp[3]));
mx21d1h mux0b4 (.s(msel), .i0(a[4]), .i1(a[3]), .z(pp[4]));
mx21d1h mux0b5 (.s(msel), .i0(a[5]), .i1(a[4]), .z(pp[5]));
mx21d1h mux0b6 (.s(msel), .i0(a[6]), .i1(a[5]), .z(pp[6]));
mx21d1h mux0b7 (.s(msel), .i0(a[7]), .i1(a[6]), .z(pp[7]));
mx21d1h mux0b8 (.s(msel), .i0(a[8]), .i1(a[7]), .z(pp[8]));
assign pp[9] = a[8]; // sign extended
an02d1h and0b0 (.a1(menb), .a2(pp[0]), .z(p[0]));
an02d1h and0b1 (.a1(menb), .a2(pp[1]), .z(p[1]));
an02d1h and0b2 (.a1(menb), .a2(pp[2]), .z(p[2]));
an02d1h and0b3 (.a1(menb), .a2(pp[3]), .z(p[3]));
an02d1h and0b4 (.a1(menb), .a2(pp[4]), .z(p[4]));
an02d1h and0b5 (.a1(menb), .a2(pp[5]), .z(p[5]));
an02d1h and0b6 (.a1(menb), .a2(pp[6]), .z(p[6]));
an02d1h and0b7 (.a1(menb), .a2(pp[7]), .z(p[7]));
an02d1h and0b8 (.a1(menb), .a2(pp[8]), .z(p[8]));
an02d1h and0b9 (.a1(menb), .a2(pp[9]), .z(p[9]));
endmodule // cc_lerp_booth0