diff --git a/src/fpu/fma/fmaalign.sv b/src/fpu/fma/fmaalign.sv index 06817d446..f9bddb9e3 100644 --- a/src/fpu/fma/fmaalign.sv +++ b/src/fpu/fma/fmaalign.sv @@ -1,4 +1,3 @@ - /////////////////////////////////////////// // fmaalign.sv // @@ -28,18 +27,18 @@ //////////////////////////////////////////////////////////////////////////////////////////////// module fmaalign import cvw::*; #(parameter cvw_t P) ( - input logic [P.NE-1:0] Xe, Ye, Ze, // biased exponents in B(NE.0) format - input logic [P.NF:0] Zm, // significand in U(0.NF) format] - input logic XZero, YZero, ZZero,// is the input zero - output logic [3*P.NF+3:0] Am, // addend aligned for addition in U(NF+5.2NF+1) - output logic ASticky, // Sticky bit calculated from the aliged addend - output logic KillProd // should the product be set to zero + input logic [P.NE-1:0] Xe, Ye, Ze, // biased exponents in B(NE.0) format + input logic [P.NF:0] Zm, // significand in U(0.NF) format] + input logic XZero, YZero, ZZero, // is the input zero + output logic [3*P.NF+3:0] Am, // addend aligned for addition in U(NF+5.2NF+1) + output logic ASticky, // Sticky bit calculated from the aliged addend + output logic KillProd // should the product be set to zero ); - logic [P.NE+1:0] ACnt; // how far to shift the addend to align with the product in Q(NE+2.0) format - logic [4*P.NF+3:0] ZmShifted; // output of the alignment shifter including sticky bits U(NF+5.3NF+1) - logic [4*P.NF+3:0] ZmPreshifted; // input to the alignment shifter U(NF+5.3NF+1) - logic KillZ; // should the addend be killed + logic [P.NE+1:0] ACnt; // how far to shift the addend to align with the product in Q(NE+2.0) format + logic [4*P.NF+3:0] ZmShifted; // output of the alignment shifter including sticky bits U(NF+5.3NF+1) + logic [4*P.NF+3:0] ZmPreshifted; // input to the alignment shifter U(NF+5.3NF+1) + logic KillZ; // should the addend be killed /////////////////////////////////////////////////////////////////////////////// // Alignment shifter @@ -51,45 +50,41 @@ module fmaalign import cvw::*; #(parameter cvw_t P) ( // This could have been done using Pe, but ACnt is on the critical path so we replicate logic for speed assign ACnt = {2'b0, Xe} + {2'b0, Ye} - {2'b0, (P.NE)'(P.BIAS)} + (P.NE+2)'(P.NF+2) - {2'b0, Ze}; - // Defualt Addition with only inital left shift - // | 53'b0 | 106'b(product) | 1'b0 | - // | addnend | + // Default Addition with only inital left shift + // | 53'b0 | 106'b(product) | 1'b0 | + // | addnend | assign ZmPreshifted = {Zm,(3*P.NF+3)'(0)}; - - assign KillProd = (ACnt[P.NE+1]&~ZZero)|XZero|YZero; - assign KillZ = $signed(ACnt)>$signed((P.NE+2)'(3)*(P.NE+2)'(P.NF)+(P.NE+2)'(3)); + assign KillProd = (ACnt[P.NE+1]&~ZZero)|XZero|YZero; + assign KillZ = $signed(ACnt)>$signed((P.NE+2)'(3)*(P.NE+2)'(P.NF)+(P.NE+2)'(3)); always_comb begin // If the product is too small to effect the sum, kill the product - - // | 53'b0 | 106'b(product) | 1'b0 | - // | addnend | + // | 53'b0 | 106'b(product) | 1'b0 | + // | addnend | if (KillProd) begin ZmShifted = {(P.NF+2)'(0), Zm, (2*P.NF+1)'(0)}; - ASticky = ~(XZero|YZero); + ASticky = ~(XZero|YZero); // If the addend is too small to effect the addition // - The addend has to shift two past the end of the product to be considered too small // - The 2 extra bits are needed for rounding - - // | 53'b0 | 106'b(product) | 1'b0 | - // | addnend | + + // | 53'b0 | 106'b(product) | 1'b0 | + // | addnend | end else if (KillZ) begin ZmShifted = 0; - ASticky = ~ZZero; + ASticky = ~ZZero; // If the Addend is shifted right - // | 53'b0 | 106'b(product) | 1'b0 | - // | addnend | + // | 53'b0 | 106'b(product) | 1'b0 | + // | addnend | end else begin ZmShifted = ZmPreshifted >> ACnt; - ASticky = |(ZmShifted[P.NF-1:0]); - + ASticky = |(ZmShifted[P.NF-1:0]); end end assign Am = ZmShifted[4*P.NF+3:P.NF]; endmodule -