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[/] [openrisc/] [trunk/] [or1200/] [rtl/] [verilog/] [or1200_fpu_post_norm_addsub.v] - Rev 494
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////////////////////////////////////////////////////////////////////// //// //// //// or1200_fpu_post_norm_addsub //// //// //// //// This file is part of the OpenRISC 1200 project //// //// http://opencores.org/project,or1k //// //// //// //// Description //// //// post-normalization entity for the addition/subtraction unit //// //// //// //// To Do: //// //// //// //// //// //// Author(s): //// //// - Original design (FPU100) - //// //// Jidan Al-eryani, jidan@gmx.net //// //// - Conv. to Verilog and inclusion in OR1200 - //// //// Julius Baxter, julius@opencores.org //// //// //// ////////////////////////////////////////////////////////////////////// // // Copyright (C) 2006, 2010 // // This source file may be used and distributed without // restriction provided that this copyright statement is not // removed from the file and that any derivative work contains // the original copyright notice and the associated disclaimer. // // THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY // EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED // TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS // FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL THE AUTHOR // OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, // INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES // (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE // GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR // BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF // LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT // OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE // POSSIBILITY OF SUCH DAMAGE. // module or1200_fpu_post_norm_addsub ( clk_i, opa_i, opb_i, fract_28_i, exp_i, sign_i, fpu_op_i, rmode_i, output_o, ine_o ); parameter FP_WIDTH = 32; parameter MUL_SERIAL = 0; // 0 for parallel multiplier, 1 for serial parameter MUL_COUNT = 11; //11 for parallel multiplier, 34 for serial parameter FRAC_WIDTH = 23; parameter EXP_WIDTH = 8; parameter ZERO_VECTOR = 31'd0; parameter INF = 31'b1111111100000000000000000000000; parameter QNAN = 31'b1111111110000000000000000000000; parameter SNAN = 31'b1111111100000000000000000000001; input clk_i; input [FP_WIDTH-1:0] opa_i; input [FP_WIDTH-1:0] opb_i; input [FRAC_WIDTH+4:0] fract_28_i; input [EXP_WIDTH-1:0] exp_i; input sign_i; input fpu_op_i; input [1:0] rmode_i; output reg [FP_WIDTH-1:0] output_o; output reg ine_o; wire [FP_WIDTH-1:0] s_opa_i; wire [FP_WIDTH-1:0] s_opb_i; wire [FRAC_WIDTH+4:0] s_fract_28_i; wire [EXP_WIDTH-1:0] s_exp_i; wire s_sign_i; wire s_fpu_op_i; wire [1:0] s_rmode_i; wire [FP_WIDTH-1:0] s_output_o; wire s_ine_o; wire s_overflow; wire [5:0] s_zeros; reg [5:0] s_shr1; reg [5:0] s_shl1; wire s_shr2, s_carry; wire [9:0] s_exp10; reg [EXP_WIDTH:0] s_expo9_1; wire [EXP_WIDTH:0] s_expo9_2; wire [EXP_WIDTH:0] s_expo9_3; reg [FRAC_WIDTH+4:0] s_fracto28_1; wire [FRAC_WIDTH+4:0] s_fracto28_2; wire [FRAC_WIDTH+4:0] s_fracto28_rnd; wire s_roundup; wire s_sticky; wire s_zero_fract; wire s_lost; wire s_infa, s_infb; wire s_nan_in, s_nan_op, s_nan_a, s_nan_b, s_nan_sign; assign s_opa_i = opa_i; assign s_opb_i = opb_i; assign s_fract_28_i = fract_28_i; assign s_exp_i = exp_i; assign s_sign_i = sign_i; assign s_fpu_op_i = fpu_op_i; assign s_rmode_i = rmode_i; // Output Register always @(posedge clk_i) begin output_o <= s_output_o; ine_o <= s_ine_o; end //*** Stage 1 **** // figure out the output exponent and how much the fraction has to be // shiftd right/left assign s_carry = s_fract_28_i[27]; reg [5:0] lzeroes; always @(s_fract_28_i) casez(s_fract_28_i[26:0]) // synopsys full_case parallel_case 27'b1??????????????????????????: lzeroes = 0; 27'b01?????????????????????????: lzeroes = 1; 27'b001????????????????????????: lzeroes = 2; 27'b0001???????????????????????: lzeroes = 3; 27'b00001??????????????????????: lzeroes = 4; 27'b000001?????????????????????: lzeroes = 5; 27'b0000001????????????????????: lzeroes = 6; 27'b00000001???????????????????: lzeroes = 7; 27'b000000001??????????????????: lzeroes = 8; 27'b0000000001?????????????????: lzeroes = 9; 27'b00000000001????????????????: lzeroes = 10; 27'b000000000001???????????????: lzeroes = 11; 27'b0000000000001??????????????: lzeroes = 12; 27'b00000000000001?????????????: lzeroes = 13; 27'b000000000000001????????????: lzeroes = 14; 27'b0000000000000001???????????: lzeroes = 15; 27'b00000000000000001??????????: lzeroes = 16; 27'b000000000000000001?????????: lzeroes = 17; 27'b0000000000000000001????????: lzeroes = 18; 27'b00000000000000000001???????: lzeroes = 19; 27'b000000000000000000001??????: lzeroes = 20; 27'b0000000000000000000001?????: lzeroes = 21; 27'b00000000000000000000001????: lzeroes = 22; 27'b000000000000000000000001???: lzeroes = 23; 27'b0000000000000000000000001??: lzeroes = 24; 27'b00000000000000000000000001?: lzeroes = 25; 27'b000000000000000000000000001: lzeroes = 26; 27'b000000000000000000000000000: lzeroes = 27; endcase assign s_zeros = s_fract_28_i[27] ? 0 : lzeroes; // negative flag & large flag & exp assign s_exp10 = {2'd0,s_exp_i} + {9'd0,s_carry} - {4'd0,s_zeros}; always @(posedge clk_i) begin if (s_exp10[9] | !(|s_exp10)) begin s_shr1 <= 0; s_expo9_1 <= 9'd1; if (|s_exp_i) s_shl1 <= s_exp_i[5:0] - 6'd1; else s_shl1 <= 0; end else if (s_exp10[8]) begin s_shr1 <= 0; s_shl1 <= 0; s_expo9_1 <= 9'b011111111; end else begin s_shr1 <= {5'd0,s_carry}; s_shl1 <= s_zeros; s_expo9_1 <= s_exp10[8:0]; end // else: !if(s_exp10[8]) end // always @ (posedge clk_i) //- // *** Stage 2 *** // Shifting the fraction and rounding always @(posedge clk_i) if (|s_shr1) s_fracto28_1 <= s_fract_28_i >> s_shr1; else s_fracto28_1 <= s_fract_28_i << s_shl1; assign s_expo9_2 = (s_fracto28_1[27:26]==2'b00) ? s_expo9_1 - 9'd1 : s_expo9_1; // round //check last bit, before and after right-shift assign s_sticky = s_fracto28_1[0] | (s_fract_28_i[0] & s_fract_28_i[27]); assign s_roundup = s_rmode_i==2'b00 ? // round to nearset even s_fracto28_1[2] & ((s_fracto28_1[1] | s_sticky) | s_fracto28_1[3]) : s_rmode_i==2'b10 ? // round up (s_fracto28_1[2] | s_fracto28_1[1] | s_sticky) & !s_sign_i: s_rmode_i==2'b11 ? // round down (s_fracto28_1[2] | s_fracto28_1[1] | s_sticky) & s_sign_i : // round to zero(truncate = no rounding) 0; assign s_fracto28_rnd = s_roundup ? s_fracto28_1+28'b0000_0000_0000_0000_0000_0000_1000 : s_fracto28_1; // ***Stage 3*** // right-shift after rounding (if necessary) assign s_shr2 = s_fracto28_rnd[27]; assign s_expo9_3 = (s_shr2 & s_expo9_2!=9'b011111111) ? s_expo9_2 + 9'b000000001 : s_expo9_2; assign s_fracto28_2 = s_shr2 ? {1'b0,s_fracto28_rnd[27:1]} : s_fracto28_rnd; ////- assign s_infa = &s_opa_i[30:23]; assign s_infb = &s_opb_i[30:23]; assign s_nan_a = s_infa & (|s_opa_i[22:0]); assign s_nan_b = s_infb & (|s_opb_i[22:0]); assign s_nan_in = s_nan_a | s_nan_b; // inf-inf=Nan assign s_nan_op = (s_infa & s_infb) & (s_opa_i[31] ^ (s_fpu_op_i ^ s_opb_i[31])); assign s_nan_sign = (s_nan_a & s_nan_b) ? s_sign_i : s_nan_a ? s_opa_i[31] : s_opb_i[31]; // check if result is inexact; assign s_lost = (s_shr1[0] & s_fract_28_i[0]) | (s_shr2 & s_fracto28_rnd[0]) | (|s_fracto28_2[2:0]); assign s_ine_o = (s_lost | s_overflow) & !(s_infa | s_infb); assign s_overflow = s_expo9_3==9'b011111111 & !(s_infa | s_infb); // '1' if fraction result is zero assign s_zero_fract = s_zeros==27 & !s_fract_28_i[27]; // Generate result assign s_output_o = (s_nan_in | s_nan_op) ? {s_nan_sign,QNAN} : (s_infa | s_infb) | s_overflow ? {s_sign_i,INF} : s_zero_fract ? {s_sign_i,ZERO_VECTOR} : {s_sign_i,s_expo9_3[7:0],s_fracto28_2[25:3]}; endmodule // or1200_fpu_post_norm_addsub
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