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[/] [thor/] [trunk/] [FT64v5/] [rtl/] [fpUnit/] [fpRes.v] - Rev 58
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/* =============================================================== (C) 2006 Robert Finch All rights reserved. rob@birdcomputer.ca fpRes.v - floating point reciprocal estimate - zero clock cycle latency - IEEE 754 representation This source code is free for use and modification for non-commercial or evaluation purposes, provided this copyright statement and disclaimer remains present in the file. If the code is modified, please state the origin and note that the code has been modified. NO WARRANTY. THIS Work, IS PROVIDEDED "AS IS" WITH NO WARRANTIES OF ANY KIND, WHETHER EXPRESS OR IMPLIED. The user must assume the entire risk of using the Work. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR ANY INCIDENTAL, CONSEQUENTIAL, OR PUNITIVE DAMAGES WHATSOEVER RELATING TO THE USE OF THIS WORK, OR YOUR RELATIONSHIP WITH THE AUTHOR. IN ADDITION, IN NO EVENT DOES THE AUTHOR AUTHORIZE YOU TO USE THE WORK IN APPLICATIONS OR SYSTEMS WHERE THE WORK'S FAILURE TO PERFORM CAN REASONABLY BE EXPECTED TO RESULT IN A SIGNIFICANT PHYSICAL INJURY, OR IN LOSS OF LIFE. ANY SUCH USE BY YOU IS ENTIRELY AT YOUR OWN RISK, AND YOU AGREE TO HOLD THE AUTHOR AND CONTRIBUTORS HARMLESS FROM ANY CLAIMS OR LOSSES RELATING TO SUCH UNAUTHORIZED USE. This multiplier/divider handles denormalized numbers. The output format is of an internal expanded representation in preparation to be fed into a normalization unit, then rounding. Basically, it's the same as the regular format except the mantissa is doubled in size, the leading two bits of which are assumed to be whole bits. Floating Point Reciprocal Estimator - to estimate the reciprocal - negate the exponent - lookup the reciprocal of the fraction - NaN's are not altered Ref: Webpack8.1i Spartan3-4 xc3s1000-4ft256 =============================================================== */ module fpRes #( parameter WID=32) ( input [WID:1] i, input [WID:1] o ); // parameter WID = 32; localparam MSB = WID-1; localparam EMSB = WID==80 ? 14 : WID==64 ? 10 : WID==48 ? 10 : WID==42 ? 10 : WID==40 ? 9 : WID==32 ? 7 : WID==24 ? 6 : 4; localparam FMSB = WID==80 ? 63 : WID==64 ? 51 : WID==48 ? 35 : WID==42 ? 29 : WID==40 ? 28 : WID==32 ? 22 : WID==24 ? 15 : 9; localparam LSB = FMSB >= 32 ? 0 : WID-FMSB; // only the first 32 bits are in the table // Decompose the operands wire sa; // sign bit wire [EMSB:0] exp; // exponent bits wire [FMSB+1:0] fract; wire inf; wire nan; reg [WID+1:1] recip; // an extra '1' is added as it is used during negation of exponent wire [2:0] expInc = recip[31] ? 1 : recip[30] ? 2 : recip[29] ? 3 : recip[28] ? 4 : 5; fpDecomp #(WID) u1 (.i(a), .sgn(sa), .exp(exp), .fract(fract), .inf(inf), .nan(nan) ); assign o = nan ? i : // nan's are not converted inf ? {sa,{WID-1{1'b0}}} : // reciprocal of infinity is zero {sa,~(exp+expInc),recip[31:LSB]<<expInc}; // estimate 1/d 8-bit accuracy always @(fract) case(fract[FMSB+1:FMSB+1-7]) 8'd001: recip=32'h10000000; 8'd002: recip=32'h80000000; 8'd003: recip=32'h55555555; 8'd004: recip=32'h40000000; 8'd005: recip=32'h33333333; 8'd006: recip=32'h2AAAAAAA; 8'd007: recip=32'h24924924; 8'd008: recip=32'h20000000; 8'd009: recip=32'h1C71C71C; 8'd010: recip=32'h19999999; 8'd011: recip=32'h1745D174; 8'd012: recip=32'h15555555; 8'd013: recip=32'h13B13B13; 8'd014: recip=32'h12492492; 8'd015: recip=32'h11111111; 8'd016: recip=32'h10000000; 8'd017: recip=32'hF0F0F0F; 8'd018: recip=32'hE38E38E; 8'd019: recip=32'hD79435E; 8'd020: recip=32'hCCCCCCC; 8'd021: recip=32'hC30C30C; 8'd022: recip=32'hBA2E8BA; 8'd023: recip=32'hB21642C; 8'd024: recip=32'hAAAAAAA; 8'd025: recip=32'hA3D70A3; 8'd026: recip=32'h9D89D89; 8'd027: recip=32'h97B425E; 8'd028: recip=32'h9249249; 8'd029: recip=32'h8D3DCB0; 8'd030: recip=32'h8888888; 8'd031: recip=32'h8421084; 8'd032: recip=32'h8000000; 8'd033: recip=32'h7C1F07C; 8'd034: recip=32'h7878787; 8'd035: recip=32'h7507507; 8'd036: recip=32'h71C71C7; 8'd037: recip=32'h6EB3E45; 8'd038: recip=32'h6BCA1AF; 8'd039: recip=32'h6906906; 8'd040: recip=32'h6666666; 8'd041: recip=32'h63E7063; 8'd042: recip=32'h6186186; 8'd043: recip=32'h5F417D0; 8'd044: recip=32'h5D1745D; 8'd045: recip=32'h5B05B05; 8'd046: recip=32'h590B216; 8'd047: recip=32'h572620A; 8'd048: recip=32'h5555555; 8'd049: recip=32'h5397829; 8'd050: recip=32'h51EB851; 8'd051: recip=32'h5050505; 8'd052: recip=32'h4EC4EC4; 8'd053: recip=32'h4D4873E; 8'd054: recip=32'h4BDA12F; 8'd055: recip=32'h4A7904A; 8'd056: recip=32'h4924924; 8'd057: recip=32'h47DC11F; 8'd058: recip=32'h469EE58; 8'd059: recip=32'h456C797; 8'd060: recip=32'h4444444; 8'd061: recip=32'h4325C53; 8'd062: recip=32'h4210842; 8'd063: recip=32'h4104104; 8'd064: recip=32'h4000000; 8'd065: recip=32'h3F03F03; 8'd066: recip=32'h3E0F83E; 8'd067: recip=32'h3D22635; 8'd068: recip=32'h3C3C3C3; 8'd069: recip=32'h3B5CC0E; 8'd070: recip=32'h3A83A83; 8'd071: recip=32'h39B0AD1; 8'd072: recip=32'h38E38E3; 8'd073: recip=32'h381C0E0; 8'd074: recip=32'h3759F22; 8'd075: recip=32'h369D036; 8'd076: recip=32'h35E50D7; 8'd077: recip=32'h3531DEC; 8'd078: recip=32'h3483483; 8'd079: recip=32'h33D91D2; 8'd080: recip=32'h3333333; 8'd081: recip=32'h329161F; 8'd082: recip=32'h31F3831; 8'd083: recip=32'h3159721; 8'd084: recip=32'h30C30C3; 8'd085: recip=32'h3030303; 8'd086: recip=32'h2FA0BE8; 8'd087: recip=32'h2F14990; 8'd088: recip=32'h2E8BA2E; 8'd089: recip=32'h2E05C0B; 8'd090: recip=32'h2D82D82; 8'd091: recip=32'h2D02D02; 8'd092: recip=32'h2C8590B; 8'd093: recip=32'h2C0B02C; 8'd094: recip=32'h2B93105; 8'd095: recip=32'h2B1DA46; 8'd096: recip=32'h2AAAAAA; 8'd097: recip=32'h2A3A0FD; 8'd098: recip=32'h29CBC14; 8'd099: recip=32'h295FAD4; 8'd100: recip=32'h28F5C28; 8'd101: recip=32'h288DF0C; 8'd102: recip=32'h2828282; 8'd103: recip=32'h27C4597; 8'd104: recip=32'h2762762; 8'd105: recip=32'h2702702; 8'd106: recip=32'h26A439F; 8'd107: recip=32'h2647C69; 8'd108: recip=32'h25ED097; 8'd109: recip=32'h2593F69; 8'd110: recip=32'h253C825; 8'd111: recip=32'h24E6A17; 8'd112: recip=32'h2492492; 8'd113: recip=32'h243F6F0; 8'd114: recip=32'h23EE08F; 8'd115: recip=32'h239E0D5; 8'd116: recip=32'h234F72C; 8'd117: recip=32'h2302302; 8'd118: recip=32'h22B63CB; 8'd119: recip=32'h226B902; 8'd120: recip=32'h2222222; 8'd121: recip=32'h21D9EAD; 8'd122: recip=32'h2192E29; 8'd123: recip=32'h214D021; 8'd124: recip=32'h2108421; 8'd125: recip=32'h20C49BA; 8'd126: recip=32'h2082082; 8'd127: recip=32'h2040810; 8'd128: recip=32'h2000000; 8'd129: recip=32'h1FC07F0; 8'd130: recip=32'h1F81F81; 8'd131: recip=32'h1F44659; 8'd132: recip=32'h1F07C1F; 8'd133: recip=32'h1ECC07B; 8'd134: recip=32'h1E9131A; 8'd135: recip=32'h1E573AC; 8'd136: recip=32'h1E1E1E1; 8'd137: recip=32'h1DE5D6E; 8'd138: recip=32'h1DAE607; 8'd139: recip=32'h1D77B65; 8'd140: recip=32'h1D41D41; 8'd141: recip=32'h1D0CB58; 8'd142: recip=32'h1CD8568; 8'd143: recip=32'h1CA4B30; 8'd144: recip=32'h1C71C71; 8'd145: recip=32'h1C3F8F0; 8'd146: recip=32'h1C0E070; 8'd147: recip=32'h1BDD2B8; 8'd148: recip=32'h1BACF91; 8'd149: recip=32'h1B7D6C3; 8'd150: recip=32'h1B4E81B; 8'd151: recip=32'h1B20364; 8'd152: recip=32'h1AF286B; 8'd153: recip=32'h1AC5701; 8'd154: recip=32'h1A98EF6; 8'd155: recip=32'h1A6D01A; 8'd156: recip=32'h1A41A41; 8'd157: recip=32'h1A16D3F; 8'd158: recip=32'h19EC8E9; 8'd159: recip=32'h19C2D14; 8'd160: recip=32'h1999999; 8'd161: recip=32'h1970E4F; 8'd162: recip=32'h1948B0F; 8'd163: recip=32'h1920FB4; 8'd164: recip=32'h18F9C18; 8'd165: recip=32'h18D3018; 8'd166: recip=32'h18ACB90; 8'd167: recip=32'h1886E5F; 8'd168: recip=32'h1861861; 8'd169: recip=32'h183C977; 8'd170: recip=32'h1818181; 8'd171: recip=32'h17F405F; 8'd172: recip=32'h17D05F4; 8'd173: recip=32'h17AD220; 8'd174: recip=32'h178A4C8; 8'd175: recip=32'h1767DCE; 8'd176: recip=32'h1745D17; 8'd177: recip=32'h1724287; 8'd178: recip=32'h1702E05; 8'd179: recip=32'h16E1F76; 8'd180: recip=32'h16C16C1; 8'd181: recip=32'h16A13CD; 8'd182: recip=32'h1681681; 8'd183: recip=32'h1661EC6; 8'd184: recip=32'h1642C85; 8'd185: recip=32'h1623FA7; 8'd186: recip=32'h1605816; 8'd187: recip=32'h15E75BB; 8'd188: recip=32'h15C9882; 8'd189: recip=32'h15AC056; 8'd190: recip=32'h158ED23; 8'd191: recip=32'h1571ED3; 8'd192: recip=32'h1555555; 8'd193: recip=32'h1539094; 8'd194: recip=32'h151D07E; 8'd195: recip=32'h1501501; 8'd196: recip=32'h14E5E0A; 8'd197: recip=32'h14CAB88; 8'd198: recip=32'h14AFD6A; 8'd199: recip=32'h149539E; 8'd200: recip=32'h147AE14; 8'd201: recip=32'h1460CBC; 8'd202: recip=32'h1446F86; 8'd203: recip=32'h142D662; 8'd204: recip=32'h1414141; 8'd205: recip=32'h13FB013; 8'd206: recip=32'h13E22CB; 8'd207: recip=32'h13C995A; 8'd208: recip=32'h13B13B1; 8'd209: recip=32'h13991C2; 8'd210: recip=32'h1381381; 8'd211: recip=32'h13698DF; 8'd212: recip=32'h13521CF; 8'd213: recip=32'h133AE45; 8'd214: recip=32'h1323E34; 8'd215: recip=32'h130D190; 8'd216: recip=32'h12F684B; 8'd217: recip=32'h12E025C; 8'd218: recip=32'h12C9FB4; 8'd219: recip=32'h12B404A; 8'd220: recip=32'h129E412; 8'd221: recip=32'h1288B01; 8'd222: recip=32'h127350B; 8'd223: recip=32'h125E227; 8'd224: recip=32'h1249249; 8'd225: recip=32'h1234567; 8'd226: recip=32'h121FB78; 8'd227: recip=32'h120B470; 8'd228: recip=32'h11F7047; 8'd229: recip=32'h11E2EF3; 8'd230: recip=32'h11CF06A; 8'd231: recip=32'h11BB4A4; 8'd232: recip=32'h11A7B96; 8'd233: recip=32'h1194538; 8'd234: recip=32'h1181181; 8'd235: recip=32'h116E068; 8'd236: recip=32'h115B1E5; 8'd237: recip=32'h11485F0; 8'd238: recip=32'h1135C81; 8'd239: recip=32'h112358E; 8'd240: recip=32'h1111111; 8'd241: recip=32'h10FEF01; 8'd242: recip=32'h10ECF56; 8'd243: recip=32'h10DB20A; 8'd244: recip=32'h10C9714; 8'd245: recip=32'h10B7E6E; 8'd246: recip=32'h10A6810; 8'd247: recip=32'h10953F3; 8'd248: recip=32'h1084210; 8'd249: recip=32'h1073260; 8'd250: recip=32'h10624DD; 8'd251: recip=32'h105197F; 8'd252: recip=32'h1041041; 8'd253: recip=32'h103091B; 8'd254: recip=32'h1020408; 8'd255: recip=32'h1010101; endcase endmodule
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