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[/] [double_fpu/] [tags/] [arelease/] [fpu_mul.v] - Rev 12
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///////////////////////////////////////////////////////////////////// //// //// //// FPU //// //// Floating Point Unit (Double precision) //// //// //// //// Author: David Lundgren //// //// davidklun@gmail.com //// //// //// ///////////////////////////////////////////////////////////////////// //// //// //// Copyright (C) 2009 David Lundgren //// //// davidklun@gmail.com //// //// //// //// 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. //// //// //// ///////////////////////////////////////////////////////////////////// `timescale 1ns / 100ps module fpu_mul( clk, rst, enable, opa, opb, sign, product_7, exponent_5); input clk; input rst; input enable; input [63:0] opa, opb; output sign; output [55:0] product_7; output [11:0] exponent_5; reg [5:0] product_shift; reg [5:0] product_shift_2; reg sign; reg [51:0] mantissa_a; reg [51:0] mantissa_b; reg [10:0] exponent_a; reg [10:0] exponent_b; reg a_is_norm; reg b_is_norm; reg a_is_zero; reg b_is_zero; reg in_zero; reg [11:0] exponent_terms; reg exponent_gt_expoffset; reg [11:0] exponent_under; reg [11:0] exponent_1; wire [11:0] exponent = 0; reg [11:0] exponent_2; reg exponent_gt_prodshift; reg [11:0] exponent_3; reg [11:0] exponent_4; reg exponent_et_zero; reg [52:0] mul_a; reg [52:0] mul_b; reg [40:0] product_a; reg [40:0] product_b; reg [40:0] product_c; reg [25:0] product_d; reg [33:0] product_e; reg [33:0] product_f; reg [35:0] product_g; reg [28:0] product_h; reg [28:0] product_i; reg [30:0] product_j; reg [41:0] sum_0; reg [35:0] sum_1; reg [41:0] sum_2; reg [35:0] sum_3; reg [36:0] sum_4; reg [27:0] sum_5; reg [29:0] sum_6; reg [36:0] sum_7; reg [30:0] sum_8; reg [105:0] product; reg [105:0] product_1; reg [105:0] product_2; reg [105:0] product_3; reg [105:0] product_4; reg [105:0] product_5; reg [105:0] product_6; reg product_lsb; // if there are any 1's in the remainder wire [55:0] product_7 = { 1'b0, product_6[105:52], product_lsb }; reg [11:0] exponent_5; always @(posedge clk) begin if (rst) begin sign <= 0; mantissa_a <= 0; mantissa_b <= 0; exponent_a <= 0; exponent_b <= 0; a_is_norm <= 0; b_is_norm <= 0; a_is_zero <= 0; b_is_zero <= 0; in_zero <= 0; exponent_terms <= 0; exponent_gt_expoffset <= 0; exponent_under <= 0; exponent_1 <= 0; exponent_2 <= 0; exponent_gt_prodshift <= 0; exponent_3 <= 0; exponent_4 <= 0; exponent_et_zero <= 0; mul_a <= 0; mul_b <= 0; product_a <= 0; product_b <= 0; product_c <= 0; product_d <= 0; product_e <= 0; product_f <= 0; product_g <= 0; product_h <= 0; product_i <= 0; product_j <= 0; sum_0 <= 0; sum_1 <= 0; sum_2 <= 0; sum_3 <= 0; sum_4 <= 0; sum_5 <= 0; sum_6 <= 0; sum_7 <= 0; sum_8 <= 0; product <= 0; product_1 <= 0; product_2 <= 0; product_3 <= 0; product_4 <= 0; product_5 <= 0; product_6 <= 0; product_lsb <= 0; exponent_5 <= 0; product_shift_2 <= 0; end else if (enable) begin sign <= opa[63] ^ opb[63]; mantissa_a <= opa[51:0]; mantissa_b <= opb[51:0]; exponent_a <= opa[62:52]; exponent_b <= opb[62:52]; a_is_norm <= |exponent_a; b_is_norm <= |exponent_b; a_is_zero <= !(|opa[62:0]); b_is_zero <= !(|opb[62:0]); in_zero <= a_is_zero | b_is_zero; exponent_terms <= exponent_a + exponent_b + !a_is_norm + !b_is_norm; exponent_gt_expoffset <= exponent_terms > 1021; exponent_under <= 1022 - exponent_terms; exponent_1 <= exponent_terms - 1022; exponent_2 <= exponent_gt_expoffset ? exponent_1 : exponent; exponent_gt_prodshift <= exponent_2 > product_shift_2; exponent_3 <= exponent_2 - product_shift; exponent_4 <= exponent_gt_prodshift ? exponent_3 : exponent; exponent_et_zero <= exponent_4 == 0; mul_a <= { a_is_norm, mantissa_a }; mul_b <= { b_is_norm, mantissa_b }; product_a <= mul_a[23:0] * mul_b[16:0]; product_b <= mul_a[23:0] * mul_b[33:17]; product_c <= mul_a[23:0] * mul_b[50:34]; product_d <= mul_a[23:0] * mul_b[52:51]; product_e <= mul_a[40:24] * mul_b[16:0]; product_f <= mul_a[40:24] * mul_b[33:17]; product_g <= mul_a[40:24] * mul_b[52:34]; product_h <= mul_a[52:41] * mul_b[16:0]; product_i <= mul_a[52:41] * mul_b[33:17]; product_j <= mul_a[52:41] * mul_b[52:34]; sum_0 <= product_a[40:17] + product_b; sum_1 <= sum_0[41:7] + product_e; sum_2 <= sum_1[35:10] + product_c; sum_3 <= sum_2[41:7] + product_h; sum_4 <= sum_3 + product_f; sum_5 <= sum_4[36:10] + product_d; sum_6 <= sum_5[27:7] + product_i; sum_7 <= sum_6 + product_g; sum_8 <= sum_7[36:17] + product_j; product <= { sum_8, sum_7[16:0], sum_5[6:0], sum_4[9:0], sum_2[6:0], sum_1[9:0], sum_0[6:0], product_a[16:0] }; product_1 <= product >> exponent_under; product_2 <= exponent_gt_expoffset ? product : product_1; product_3 <= product_2 << product_shift_2; product_4 <= product_2 << exponent_2; product_5 <= exponent_gt_prodshift ? product_3 : product_4; product_6 <= exponent_et_zero ? product_5 >> 1 : product_5; product_lsb <= |product_6[51:0]; exponent_5 <= in_zero ? 12'b0 : exponent_4; product_shift_2 <= product_shift; // redundant register // reduces fanout on product_shift end end always @(product) casex(product) 106'b1?????????????????????????????????????????????????????????????????????????????????????????????????????????: product_shift <= 0; 106'b01????????????????????????????????????????????????????????????????????????????????????????????????????????: product_shift <= 1; 106'b001???????????????????????????????????????????????????????????????????????????????????????????????????????: product_shift <= 2; 106'b0001??????????????????????????????????????????????????????????????????????????????????????????????????????: product_shift <= 3; 106'b00001?????????????????????????????????????????????????????????????????????????????????????????????????????: product_shift <= 4; 106'b000001????????????????????????????????????????????????????????????????????????????????????????????????????: product_shift <= 5; 106'b0000001???????????????????????????????????????????????????????????????????????????????????????????????????: product_shift <= 6; 106'b00000001??????????????????????????????????????????????????????????????????????????????????????????????????: product_shift <= 7; 106'b000000001?????????????????????????????????????????????????????????????????????????????????????????????????: product_shift <= 8; 106'b0000000001????????????????????????????????????????????????????????????????????????????????????????????????: product_shift <= 9; 106'b00000000001???????????????????????????????????????????????????????????????????????????????????????????????: product_shift <= 10; 106'b000000000001??????????????????????????????????????????????????????????????????????????????????????????????: product_shift <= 11; 106'b0000000000001?????????????????????????????????????????????????????????????????????????????????????????????: product_shift <= 12; 106'b00000000000001????????????????????????????????????????????????????????????????????????????????????????????: product_shift <= 13; 106'b000000000000001???????????????????????????????????????????????????????????????????????????????????????????: product_shift <= 14; 106'b0000000000000001??????????????????????????????????????????????????????????????????????????????????????????: product_shift <= 15; 106'b00000000000000001?????????????????????????????????????????????????????????????????????????????????????????: product_shift <= 16; 106'b000000000000000001????????????????????????????????????????????????????????????????????????????????????????: product_shift <= 17; 106'b0000000000000000001???????????????????????????????????????????????????????????????????????????????????????: product_shift <= 18; 106'b00000000000000000001??????????????????????????????????????????????????????????????????????????????????????: product_shift <= 19; 106'b000000000000000000001?????????????????????????????????????????????????????????????????????????????????????: product_shift <= 20; 106'b0000000000000000000001????????????????????????????????????????????????????????????????????????????????????: product_shift <= 21; 106'b00000000000000000000001???????????????????????????????????????????????????????????????????????????????????: product_shift <= 22; 106'b000000000000000000000001??????????????????????????????????????????????????????????????????????????????????: product_shift <= 23; 106'b0000000000000000000000001?????????????????????????????????????????????????????????????????????????????????: product_shift <= 24; 106'b00000000000000000000000001????????????????????????????????????????????????????????????????????????????????: product_shift <= 25; 106'b000000000000000000000000001???????????????????????????????????????????????????????????????????????????????: product_shift <= 26; 106'b0000000000000000000000000001??????????????????????????????????????????????????????????????????????????????: product_shift <= 27; 106'b00000000000000000000000000001?????????????????????????????????????????????????????????????????????????????: product_shift <= 28; 106'b000000000000000000000000000001????????????????????????????????????????????????????????????????????????????: product_shift <= 29; 106'b0000000000000000000000000000001???????????????????????????????????????????????????????????????????????????: product_shift <= 30; 106'b00000000000000000000000000000001??????????????????????????????????????????????????????????????????????????: product_shift <= 31; 106'b000000000000000000000000000000001?????????????????????????????????????????????????????????????????????????: product_shift <= 32; 106'b0000000000000000000000000000000001????????????????????????????????????????????????????????????????????????: product_shift <= 33; 106'b00000000000000000000000000000000001???????????????????????????????????????????????????????????????????????: product_shift <= 34; 106'b000000000000000000000000000000000001??????????????????????????????????????????????????????????????????????: product_shift <= 35; 106'b0000000000000000000000000000000000001?????????????????????????????????????????????????????????????????????: product_shift <= 36; 106'b00000000000000000000000000000000000001????????????????????????????????????????????????????????????????????: product_shift <= 37; 106'b000000000000000000000000000000000000001???????????????????????????????????????????????????????????????????: product_shift <= 38; 106'b0000000000000000000000000000000000000001??????????????????????????????????????????????????????????????????: product_shift <= 39; 106'b00000000000000000000000000000000000000001?????????????????????????????????????????????????????????????????: product_shift <= 40; 106'b000000000000000000000000000000000000000001????????????????????????????????????????????????????????????????: product_shift <= 41; 106'b0000000000000000000000000000000000000000001???????????????????????????????????????????????????????????????: product_shift <= 42; 106'b00000000000000000000000000000000000000000001??????????????????????????????????????????????????????????????: product_shift <= 43; 106'b000000000000000000000000000000000000000000001?????????????????????????????????????????????????????????????: product_shift <= 44; 106'b0000000000000000000000000000000000000000000001????????????????????????????????????????????????????????????: product_shift <= 45; 106'b00000000000000000000000000000000000000000000001???????????????????????????????????????????????????????????: product_shift <= 46; 106'b000000000000000000000000000000000000000000000001??????????????????????????????????????????????????????????: product_shift <= 47; 106'b0000000000000000000000000000000000000000000000001?????????????????????????????????????????????????????????: product_shift <= 48; 106'b00000000000000000000000000000000000000000000000001????????????????????????????????????????????????????????: product_shift <= 49; 106'b000000000000000000000000000000000000000000000000001???????????????????????????????????????????????????????: product_shift <= 50; 106'b0000000000000000000000000000000000000000000000000001??????????????????????????????????????????????????????: product_shift <= 51; 106'b00000000000000000000000000000000000000000000000000001?????????????????????????????????????????????????????: product_shift <= 52; 106'b000000000000000000000000000000000000000000000000000000????????????????????????????????????????????????????: product_shift <= 53; // It's not necessary to go past 53, because you will only get more than 53 zeros // when multiplying 2 denormalized numbers together, in which case you will underflow endcase endmodule
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