root/src/dps8/dps8_decimal.c

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DEFINITIONS

This source file includes following definitions.
  1. decContextDefaultDPS8
  2. decContextDefaultDPS8Mul
  3. decBCD9ToNumber
  4. formatDecimal
  5. decCompare
  6. decCompareMAG

   1 /*
   2  * vim: filetype=c:tabstop=4:ai:expandtab
   3  * SPDX-License-Identifier: ICU
   4  * scspell-id: 9868415b-f62d-11ec-9c75-80ee73e9b8e7
   5  *
   6  * ---------------------------------------------------------------------------
   7  *
   8  * Copyright (c) 2000-2009 IBM Corporation
   9  * Copyright (c) 2012-2016 Harry Reed
  10  * Copyright (c) 2013-2016 Charles Anthony
  11  * Copyright (c) 2017 Michal Tomek
  12  * Copyright (c) 2021-2023 The DPS8M Development Team
  13  *
  14  * All rights reserved.
  15  *
  16  * This software is made available under the terms of the ICU
  17  * License, version 1.8.1 or later.  For more details, see the
  18  * LICENSE.md file at the top-level directory of this distribution.
  19  *
  20  * ---------------------------------------------------------------------------
  21  */
  22 
  23 #include <stdio.h>
  24 
  25 #include "dps8.h"
  26 #include "dps8_sys.h"
  27 #include "dps8_faults.h"
  28 #include "dps8_scu.h"
  29 #include "dps8_iom.h"
  30 #include "dps8_cable.h"
  31 #include "dps8_cpu.h"
  32 #include "dps8_decimal.h"
  33 #include "dps8_eis.h"
  34 #include "dps8_utils.h"
  35 
  36 /* ------------------------------------------------------------------ */
  37 /* HWR 6/28/14 18:54 derived from ......                              */
  38 /*     decContextDefault(...)                                         */
  39 /*                                                                    */
  40 /* decContextDefaultDPS8 -- initialize a context structure            */
  41 /*                                                                    */
  42 /* Similar to decContextDefault EXCEPT digits are set to 65 for our   */
  43 /* dps8 simulator (add additional features as required                */
  44 /*                                                                    */
  45 /* ------------------------------------------------------------------ */
  46 decContext * decContextDefaultDPS8(decContext *context)
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  47 {
  48     decContextDefault(context, DEC_INIT_BASE);
  49     context->traps=0;
  50 
  51     context->digits = 65;
  52 
  53     return context;
  54 }
  55 
  56 /* ------------------------------------------------------------------ */
  57 /* HWR 3/21/16 19:54 derived from ......                              */
  58 /* decContextDefault(...)                                             */
  59 /*                                                                    */
  60 /* decContextDefaultDPS8 -- initialize a context structure            */
  61 /*                                                                    */
  62 /* Similar to decContextDefault EXCEPT digits are set to 126 for our  */
  63 /* dps8 simulators mpXd instructions                                  */
  64 /*                                                                    */
  65 /* ------------------------------------------------------------------ */
  66 decContext * decContextDefaultDPS8Mul(decContext *context)
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  67 {
  68     decContextDefault(context, DEC_INIT_BASE);
  69     context->traps  = 0;
  70 
  71     context->digits = 63 + 63;   // worse case for multiply
  72 
  73     return context;
  74 }
  75 
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  97 decNumber * decBCD9ToNumber(const word9 *bcd, Int length, const Int scale, decNumber *dn)
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  98 {
  99     const word9 *last=bcd+length-1;  // -> last byte
 100     const word9 *first;              // -> first non-zero byte
 101     uInt  nib;                       // work nibble
 102     Unit  *up=dn->lsu;               // output pointer
 103     Int   digits;                    // digits count
 104     Int   cut=0;                     // phase of output
 105 
 106     decNumberZero(dn);               // default result
 107     //last = &bcd[length-1];
 108     //nib = *last & 0x0f;                // get the sign
 109     //if (nib==DECPMINUS || nib==DECPMINUSALT) dn->bits=DECNEG;
 110     //else if (nib<=9) return NULL;   // not a sign nibble
 111 
 112     // skip leading zero bytes [final byte is always non-zero, due to sign]
 113     //for (first=bcd; *first==0;) first++;
 114 
 115     //Also, a bug in decBCD9ToNumber; in the input is all zeros, the skip leading zeros code wanders off the end of the input buffer....
 116     for (first=bcd; *first==0 && first <= last;)
 117         first++;
 118 
 119     digits=(Int)(last-first)+1;              // calculate digits ..
 120     //if ((*first & 0xf0)==0) digits--;     // adjust for leading zero nibble
 121     if (digits!=0)
 122        dn->digits=digits;     // count of actual digits [if 0,
 123     // leave as 1]
 124 
 125     // check the adjusted exponent; note that scale could be unbounded
 126     dn->exponent=-scale;                 // set the exponent
 127     if (scale>=0)                        // usual case
 128     {
 129         if ((dn->digits-scale-1)<-DECNUMMAXE)        // underflow
 130         {
 131             decNumberZero(dn);
 132             //return NULL;
 133             // XXX check subfault
 134             doFault (FAULT_IPR, fst_ill_proc, "decBCD9ToNumber underflow");
 135         }
 136     }
 137     else  // -ve scale; +ve exponent
 138     {
 139         // need to be careful to avoid wrap, here, also BADINT case
 140         if ((scale<-DECNUMMAXE)            // overflow even without digits
 141             || ((dn->digits-scale-1)>DECNUMMAXE))   // overflow
 142         {
 143             decNumberZero(dn);
 144             //return NULL;
 145             // XXX check subfault
 146             doFault (FAULT_IPR, fst_ill_proc, "decBCD9ToNumber overflow");
 147         }
 148     }
 149     if (digits==0)
 150       return dn;             // result was zero
 151 
 152     // copy the digits to the number's units, starting at the lsu
 153     // [unrolled]
 154     for (;last >= bcd;)                             // forever
 155     {
 156         nib=(unsigned)(*last & 0x0f);
 157         // got a digit, in nib
 158         //if (nib>9) {decNumberZero(dn); return NULL;}    // bad digit
 159         if (nib > 9)
 160           doFault (FAULT_IPR, fst_ill_dig, "decBCD9ToNumber ill digit");
 161 
 162         if (cut==0)
 163           *up=(Unit)nib;
 164         else
 165           *up=(Unit)(*up+nib*DECPOWERS[cut]);
 166         digits--;
 167         if (digits==0)
 168           break;               // got them all
 169         cut++;
 170         if (cut==DECDPUN)
 171         {
 172             up++;
 173             cut=0;
 174         }
 175         last--;                             // ready for next
 176 
 177         //        nib = *last & 0x0f;                // get right nibble
 178         //        if (nib>9) {decNumberZero(dn); return NULL;}
 179         //
 180         //        // got a digit, in nib
 181         //        if (cut==0) *up=(Unit)nib;
 182         //        else *up=(Unit)(*up+nib*DECPOWERS[cut]);
 183         //        digits--;
 184         //        if (digits==0) break;               // got them all
 185         //        cut++;
 186         //        if (cut==DECDPUN) {
 187         //            up++;
 188         //            cut=0;
 189         //        }
 190     } // forever
 191 
 192     return dn;
 193 } // decBCD9ToNumber
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 705 char *formatDecimal (uint8_t * out, decContext *set, decNumber *r, int nout, int s, int sf, bool R, bool *OVR, bool *TRUNC) {
     /* [previous][next][first][last][top][bottom][index][help] */
 706   decNumber _sf;
 707   decNumber _r2;
 708   decNumber * r2 = & _r2;
 709   enum rounding safeR = decContextGetRounding (set);         // save rounding mode
 710   int safe = set->digits;
 711 
 712   * OVR = false;
 713   * TRUNC = false;
 714 
 715   // CSFL isn't rescaled and can't overflow
 716   if (s != CSFL) {
 717 
 718     // rescale to sf first
 719     // AL39: If N2 is not large enough to hold the integer part of C(Y-charn1) _as rescaled by SF2_, an overflow condition exists
 720     // ET 336
 721     if (sf != r->exponent) {
 722       if (!R) {
 723         decContextSetRounding (set, DEC_ROUND_DOWN);     // Round towards 0 (truncation). ISOLTS 815 09b
 724         if (sf > r->exponent) // ET 330: truncation due to: output sf > input sf or exponent
 725           * TRUNC = true;
 726       }
 727       decNumberFromInt32 (& _sf, sf);
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 741       if (r->exponent > sf)
 742         set->digits = min (DECNUMDIGITS, max (set->digits, r->digits + r->exponent - sf));
 743       decNumberRescale (r, r, & _sf, set);
 744       if (decContextGetStatus (set) == DEC_Invalid_operation) {
 745         //sim_debug (DBG_TRACE, & cpu_dev, "formatD DEC_Invalid_operation\r\n");
 746         decNumberZero (r);
 747         * OVR = true;
 748       }
 749       set->digits = safe;
 750 
 751 
 752     }
 753 
 754     // check for overflow and if it occurs, adjust the operand
 755 
 756     decContextSetRounding (set, DEC_ROUND_DOWN);     // Round towards 0 (truncation).
 757     decNumberToIntegralValue (r2, r, set);
 758 
 759     int r2digits = r2->digits;
 760     if (decNumberIsZero (r2))
 761       r2digits = 0;
 762 
 763     // if sf< 0, this reduces number of integer slots available
 764     // if sf>=0, this doesn't change anything, nout integer slots are available
 765     // ET 275, ET 336
 766     if (nout + min (sf,0) < r2digits) {
 767 
 768       // discard overflowing digits
 769       // note that this may set zero flag: ISOLTS-810 01l
 770       set->digits = r2digits - (nout + min (sf,0));
 771       decNumberPlus (r2, r, set);
 772       set->digits = safe;
 773 
 774       decNumberSubtract(r, r, r2, set);
 775 
 776       * OVR = true;
 777 
 778     }
 779     decContextSetRounding (set, safeR);
 780 
 781   }
 782 
 783   if (nout < r->digits) { // not enough space to move all digits
 784     // round or truncate
 785     if (! R) {
 786       decContextSetRounding(set, DEC_ROUND_DOWN);     // Round towards 0 (truncation).
 787       // truncation flag is independent of whether overflow occurred: ISOLTS-810 01k, 815 09b
 788       * TRUNC = true;
 789     }
 790     set->digits = nout;
 791     decNumberPlus (r, r, set);
 792     set->digits = safe;
 793 
 794     decContextSetRounding (set, safeR);              // restore rounding mode
 795   }
 796 
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 800 
 801   // write out the digits
 802   // note that even CSFL is aligned right - ISOLTS-810 05d
 803   uint8_t tmp[256];
 804   decNumberGetBCD (r,tmp);
 805   int justif = nout - r->digits;
 806   for (int i = 0; i < nout; i ++) {
 807     if (i < justif)
 808       out [i] = '0';
 809     else
 810       out [i] = tmp [i - justif] + '0';
 811   }
 812   out [nout] = 0;
 813 
 814   return (char *) out;
 815 }
 816 
 817 #ifndef QUIET_UNUSED
 818 // If the lhs is less than the rhs in the total order then the number
 819 // will be set to the value -1. If they are equal, then number is set
 820 // to 0. If the lhs is greater than the rhs then the number will be
 821 // set to the value 1.
 822 int decCompare(decNumber *lhs, decNumber *rhs, decContext *set)
     /* [previous][next][first][last][top][bottom][index][help] */
 823 {
 824     decNumber _cmp, *cmp;
 825     cmp = decNumberCompareTotal(&_cmp, lhs, rhs, set);
 826 
 827     if (decNumberIsZero(cmp))
 828         return 0;   // lhs == rhs
 829 
 830     if (decNumberIsNegative(cmp))
 831         return -1;  // lhs < rhs
 832 
 833     return 1;       // lhs > rhs
 834 }
 835 #endif
 836 
 837 int decCompareMAG(decNumber *lhs, decNumber *rhs, decContext *set)
     /* [previous][next][first][last][top][bottom][index][help] */
 838 {
 839     decNumber _cmpm, *cmpm;
 840     cmpm = decNumberCompareTotalMag(&_cmpm, lhs, rhs, set);
 841 
 842     if (decNumberIsZero(cmpm))
 843         return 0;   // lhs == rhs
 844 
 845     if (decNumberIsNegative(cmpm))
 846         return -1;  // lhs < rhs
 847 
 848     return 1;       // lhs > rhs
 849 }
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