Return to fpu_explode.c CVS log

Up to [Isaki's NoNo m68k/m88k emulator] / nono / fpe

Annotation of nono/fpe/fpu_explode.c, revision 1.1

1.1     ! root        1: /*     $NetBSD: fpu_explode.c,v 1.15 2015/02/05 12:23:27 isaki Exp $ */
        !             2: 
        !             3: /*
        !             4:  * Copyright (c) 1992, 1993
        !             5:  *     The Regents of the University of California.  All rights reserved.
        !             6:  *
        !             7:  * This software was developed by the Computer Systems Engineering group
        !             8:  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
        !             9:  * contributed to Berkeley.
        !            10:  *
        !            11:  * All advertising materials mentioning features or use of this software
        !            12:  * must display the following acknowledgement:
        !            13:  *     This product includes software developed by the University of
        !            14:  *     California, Lawrence Berkeley Laboratory.
        !            15:  *
        !            16:  * Redistribution and use in source and binary forms, with or without
        !            17:  * modification, are permitted provided that the following conditions
        !            18:  * are met:
        !            19:  * 1. Redistributions of source code must retain the above copyright
        !            20:  *    notice, this list of conditions and the following disclaimer.
        !            21:  * 2. Redistributions in binary form must reproduce the above copyright
        !            22:  *    notice, this list of conditions and the following disclaimer in the
        !            23:  *    documentation and/or other materials provided with the distribution.
        !            24:  * 3. Neither the name of the University nor the names of its contributors
        !            25:  *    may be used to endorse or promote products derived from this software
        !            26:  *    without specific prior written permission.
        !            27:  *
        !            28:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            29:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            30:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            31:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            32:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            33:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            34:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            35:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            36:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            37:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            38:  * SUCH DAMAGE.
        !            39:  *
        !            40:  *     @(#)fpu_explode.c       8.1 (Berkeley) 6/11/93
        !            41:  */
        !            42: 
        !            43: /*
        !            44:  * FPU subroutines: `explode' the machine's `packed binary' format numbers
        !            45:  * into our internal format.
        !            46:  */
        !            47: 
        !            48: #include "fpu_emulate.h"
        !            49: 
        !            50: 
        !            51: /* Conversion to internal format -- note asymmetry. */
        !            52: static int     fpu_itof(struct fpn *fp, uint32_t i);
        !            53: static int     fpu_stof(struct fpn *fp, uint32_t i);
        !            54: static int     fpu_dtof(struct fpn *fp, uint32_t i, uint32_t j);
        !            55: static int     fpu_xtof(struct fpn *fp, uint32_t i, uint32_t j, uint32_t k);
        !            56: 
        !            57: /*
        !            58:  * N.B.: in all of the following, we assume the FP format is
        !            59:  *
        !            60:  *     ---------------------------
        !            61:  *     | s | exponent | fraction |
        !            62:  *     ---------------------------
        !            63:  *
        !            64:  * (which represents -1**s * 1.fraction * 2**exponent), so that the
        !            65:  * sign bit is way at the top (bit 31), the exponent is next, and
        !            66:  * then the remaining bits mark the fraction.  A zero exponent means
        !            67:  * zero or denormalized (0.fraction rather than 1.fraction), and the
        !            68:  * maximum possible exponent, 2bias+1, signals inf (fraction==0) or NaN.
        !            69:  *
        !            70:  * Since the sign bit is always the topmost bit---this holds even for
        !            71:  * integers---we set that outside all the *tof functions.  Each function
        !            72:  * returns the class code for the new number (but note that we use
        !            73:  * FPC_QNAN for all NaNs; fpu_explode will fix this if appropriate).
        !            74:  */
        !            75: 
        !            76: /*
        !            77:  * int -> fpn.
        !            78:  */
        !            79: static int
        !            80: fpu_itof(struct fpn *fp, uint32_t i)
        !            81: {
        !            82: 
        !            83:        if (i == 0)
        !            84:                return (FPC_ZERO);
        !            85:        /*
        !            86:         * The value FP_1 represents 2^FP_LG, so set the exponent
        !            87:         * there and let normalization fix it up.  Convert negative
        !            88:         * numbers to sign-and-magnitude.  Note that this relies on
        !            89:         * fpu_norm()'s handling of `supernormals'; see fpu_subr.c.
        !            90:         */
        !            91:        fp->fp_exp = FP_LG;
        !            92:        fp->fp_mant[0] = (int)i < 0 ? -i : i;
        !            93:        fp->fp_mant[1] = 0;
        !            94:        fp->fp_mant[2] = 0;
        !            95:        fpu_norm(fp);
        !            96:        return (FPC_NUM);
        !            97: }
        !            98: 
        !            99: #define        mask(nbits) ((1 << (nbits)) - 1)
        !           100: 
        !           101: /*
        !           102:  * All external floating formats convert to internal in the same manner,
        !           103:  * as defined here.  Note that only normals get an implied 1.0 inserted.
        !           104:  */
        !           105: #define        FP_TOF(exp, expbias, allfrac, f0, f1, f2, f3) \
        !           106:        if (exp == 0) { \
        !           107:                if (allfrac == 0) \
        !           108:                        return (FPC_ZERO); \
        !           109:                fp->fp_exp = 1 - expbias; \
        !           110:                fp->fp_mant[0] = f0; \
        !           111:                fp->fp_mant[1] = f1; \
        !           112:                fp->fp_mant[2] = f2; \
        !           113:                fpu_norm(fp); \
        !           114:                return (FPC_NUM); \
        !           115:        } \
        !           116:        if (exp == (2 * expbias + 1)) { \
        !           117:                if (allfrac == 0) \
        !           118:                        return (FPC_INF); \
        !           119:                fp->fp_mant[0] = f0; \
        !           120:                fp->fp_mant[1] = f1; \
        !           121:                fp->fp_mant[2] = f2; \
        !           122:                return (FPC_QNAN); \
        !           123:        } \
        !           124:        fp->fp_exp = exp - expbias; \
        !           125:        fp->fp_mant[0] = FP_1 | f0; \
        !           126:        fp->fp_mant[1] = f1; \
        !           127:        fp->fp_mant[2] = f2; \
        !           128:        return (FPC_NUM)
        !           129: 
        !           130: /*
        !           131:  * 32-bit single precision -> fpn.
        !           132:  * We assume a single occupies at most (64-FP_LG) bits in the internal
        !           133:  * format: i.e., needs at most fp_mant[0] and fp_mant[1].
        !           134:  */
        !           135: static int
        !           136: fpu_stof(struct fpn *fp, uint32_t i)
        !           137: {
        !           138:        int exp;
        !           139:        uint32_t frac, f0, f1;
        !           140: #define SNG_SHIFT (SNG_FRACBITS - FP_LG)
        !           141: 
        !           142:        exp = (i >> (32 - 1 - SNG_EXPBITS)) & mask(SNG_EXPBITS);
        !           143:        frac = i & mask(SNG_FRACBITS);
        !           144:        f0 = frac >> SNG_SHIFT;
        !           145:        f1 = frac << (32 - SNG_SHIFT);
        !           146:        FP_TOF(exp, SNG_EXP_BIAS, frac, f0, f1, 0, 0);
        !           147: }
        !           148: 
        !           149: /*
        !           150:  * 64-bit double -> fpn.
        !           151:  * We assume this uses at most (96-FP_LG) bits.
        !           152:  */
        !           153: static int
        !           154: fpu_dtof(struct fpn *fp, uint32_t i, uint32_t j)
        !           155: {
        !           156:        int exp;
        !           157:        uint32_t frac, f0, f1, f2;
        !           158: #define DBL_SHIFT (DBL_FRACBITS - 32 - FP_LG)
        !           159: 
        !           160:        exp = (i >> (32 - 1 - DBL_EXPBITS)) & mask(DBL_EXPBITS);
        !           161:        frac = i & mask(DBL_FRACBITS - 32);
        !           162:        f0 = frac >> DBL_SHIFT;
        !           163:        f1 = (frac << (32 - DBL_SHIFT)) | (j >> DBL_SHIFT);
        !           164:        f2 = j << (32 - DBL_SHIFT);
        !           165:        frac |= j;
        !           166:        FP_TOF(exp, DBL_EXP_BIAS, frac, f0, f1, f2, 0);
        !           167: }
        !           168: 
        !           169: /*
        !           170:  * 96-bit extended -> fpn.
        !           171:  */
        !           172: static int
        !           173: fpu_xtof(struct fpn *fp, uint32_t i, uint32_t j, uint32_t k)
        !           174: {
        !           175:        int exp;
        !           176:        uint32_t f0, f1, f2;
        !           177: #define EXT_SHIFT (EXT_FRACBITS - 1 - 32 - FP_LG)
        !           178: 
        !           179:        exp = (i >> (32 - 1 - EXT_EXPBITS)) & mask(EXT_EXPBITS);
        !           180:        f0 = j >> EXT_SHIFT;
        !           181:        f1 = (j << (32 - EXT_SHIFT)) | (k >> EXT_SHIFT);
        !           182:        f2 = k << (32 - EXT_SHIFT);
        !           183: 
        !           184:        /* m68k extended does not imply denormal by exp==0 */
        !           185:        if (exp == 0) {
        !           186:                if ((j | k) == 0)
        !           187:                        return (FPC_ZERO);
        !           188:                fp->fp_exp = - EXT_EXP_BIAS;
        !           189:                fp->fp_mant[0] = f0;
        !           190:                fp->fp_mant[1] = f1;
        !           191:                fp->fp_mant[2] = f2;
        !           192:                fpu_norm(fp);
        !           193:                return (FPC_NUM);
        !           194:        }
        !           195:        if (exp == (2 * EXT_EXP_BIAS + 1)) {
        !           196:                /* MSB is an integer part and don't care */
        !           197:                if ((j & 0x7fffffff) == 0 && k == 0)
        !           198:                        return (FPC_INF);
        !           199:                fp->fp_mant[0] = f0;
        !           200:                fp->fp_mant[1] = f1;
        !           201:                fp->fp_mant[2] = f2;
        !           202:                return (FPC_QNAN);
        !           203:        }
        !           204:        fp->fp_exp = exp - EXT_EXP_BIAS;
        !           205:        fp->fp_mant[0] = FP_1 | f0;
        !           206:        fp->fp_mant[1] = f1;
        !           207:        fp->fp_mant[2] = f2;
        !           208:        return (FPC_NUM);
        !           209: }
        !           210: 
        !           211: #if defined(XM6i_FPE)
        !           212: /*
        !           213:  * 96-bit packed BCD -> fpn.
        !           214:  */
        !           215: static int
        !           216: fpu_ptof(struct fpemu *fe, struct fpn *fp, const uint32_t *space)
        !           217: {
        !           218:        struct fpn frac;
        !           219:        struct fpn digit;
        !           220:        struct fpn exp;
        !           221:        struct fpn *r;
        !           222:        uint32_t d;
        !           223:        uint32_t d0;
        !           224:        uint32_t e;
        !           225:        int i;
        !           226:        int j;
        !           227: 
        !           228:        if ((space[0] & 0x7fff0000) == 0x7fff0000) {
        !           229:                fp->fp_sign = (space[0] & 0x80000000) ? 1 : 0;
        !           230:                if ((space[1] | space[2]) == 0) {
        !           231:                        /* infinity */
        !           232:                        return FPC_INF;
        !           233:                } else {
        !           234:                        /* NAN */
        !           235:                        fp->fp_mant[0] = space[1] >> EXT_SHIFT;
        !           236:                        fp->fp_mant[1] =
        !           237:                                (space[1] << (32 - EXT_SHIFT)) | (space[2] >> EXT_SHIFT);
        !           238:                        fp->fp_mant[2] = space[2] << (32 - EXT_SHIFT);
        !           239: 
        !           240:                        return FPC_QNAN;
        !           241:                }
        !           242:        }
        !           243: 
        !           244:        /* 初期化 */
        !           245:        fpu_const(&frac, FPU_CONST_0);
        !           246: 
        !           247:        /* DIGIT 16 を取り出す */
        !           248:        d = space[0] & 0x0f;
        !           249:        fpu_explode(fe, &frac, FTYPE_LNG, &d);
        !           250: 
        !           251:        /* DIGIT15..DIGIT0 を取り出す */
        !           252:        for (i = 0; i < 2; i++) {
        !           253:                d0 = space[i + 1];
        !           254:                for (j = 0; j < 8; j++) {
        !           255:                        /* frac *= 10 */
        !           256:                        CPYFPN(&fe->fe_f1, &frac);
        !           257:                        fpu_const(&fe->fe_f2, FPU_CONST_10);
        !           258:                        r = fpu_mul(fe);
        !           259: 
        !           260:                        d = (d0 & 0xf0000000) >> 28;
        !           261:                        d0 <<= 4;
        !           262: 
        !           263:                        /* 1桁追加する */
        !           264:                        fpu_explode(fe, &digit, FTYPE_LNG, &d);
        !           265:                        CPYFPN(&fe->fe_f1, r);
        !           266:                        CPYFPN(&fe->fe_f2, &digit);
        !           267:                        r = fpu_add(fe);
        !           268: 
        !           269:                        CPYFPN(&frac, r);
        !           270:                }
        !           271:        }
        !           272: 
        !           273:        /* 仮数部の符号 */
        !           274:        if (space[0] & 0x80000000) {
        !           275:                frac.fp_sign = 1;
        !           276:        }
        !           277: 
        !           278:        /* (EXP3) は調査していないので未サポート */
        !           279:        e = ((space[0] & 0x0f000000) >> 24) * 100
        !           280:          + ((space[0] & 0x00f00000) >> 20) * 10
        !           281:          + ((space[0] & 0x000f0000) >> 16) * 1;
        !           282: 
        !           283:        /* 指数部の符号 */
        !           284:        if (space[0] & 0x40000000) {
        !           285:                e = -e;
        !           286:        }
        !           287: 
        !           288:        /* 小数点位置補正 */
        !           289:        e -= 16;
        !           290: 
        !           291:        /* 10^e を計算 */
        !           292:        fpu_explode(fe, &exp, FTYPE_LNG, &e);
        !           293:        CPYFPN(&fe->fe_f2, &exp);
        !           294:        r = fpu_tentox(fe);
        !           295: 
        !           296:        /* かけてできあがり */
        !           297:        CPYFPN(&fe->fe_f2, r);
        !           298:        CPYFPN(&fe->fe_f1, &frac);
        !           299:        r = fpu_mul(fe);
        !           300:        CPYFPN(fp, r);
        !           301: 
        !           302:        if (ISZERO(fp)) {
        !           303:                return FPC_ZERO;
        !           304:        }
        !           305:        return FPC_NUM;
        !           306: }
        !           307: #endif /* XM6i_FPE */
        !           308: 
        !           309: /*
        !           310:  * Explode the contents of a memory operand.
        !           311:  */
        !           312: void
        !           313: fpu_explode(struct fpemu *fe, struct fpn *fp, int type, const uint32_t *space)
        !           314: {
        !           315:        uint32_t s;
        !           316: 
        !           317:        s = space[0];
        !           318:        fp->fp_sign = s >> 31;
        !           319:        fp->fp_sticky = 0;
        !           320:        switch (type) {
        !           321: 
        !           322:        case FTYPE_BYT:
        !           323:                s >>= 8;
        !           324:        case FTYPE_WRD:
        !           325:                s >>= 16;
        !           326:        case FTYPE_LNG:
        !           327:                s = fpu_itof(fp, s);
        !           328:                break;
        !           329: 
        !           330:        case FTYPE_SNG:
        !           331:                s = fpu_stof(fp, s);
        !           332:                break;
        !           333: 
        !           334:        case FTYPE_DBL:
        !           335:                s = fpu_dtof(fp, s, space[1]);
        !           336:                break;
        !           337: 
        !           338:        case FTYPE_EXT:
        !           339:                s = fpu_xtof(fp, s, space[1], space[2]);
        !           340:                break;
        !           341: 
        !           342: #if defined(XM6i_FPE)
        !           343:        case FTYPE_BCD:
        !           344:                s = fpu_ptof(fe, fp, space);
        !           345:                break;
        !           346: #endif
        !           347: 
        !           348:        default:
        !           349: #if defined(XM6i_FPE)
        !           350:                /* 何も出来ることがない */
        !           351:                break;
        !           352: #else
        !           353:                panic("fpu_explode");
        !           354: #endif
        !           355:        }
        !           356:        if (s == FPC_QNAN && (fp->fp_mant[0] & FP_QUIETBIT) == 0) {
        !           357:                /*
        !           358:                 * Input is a signalling NaN.  All operations that return
        !           359:                 * an input NaN operand put it through a ``NaN conversion'',
        !           360:                 * which basically just means ``turn on the quiet bit''.
        !           361:                 * We do this here so that all NaNs internally look quiet
        !           362:                 * (we can tell signalling ones by their class).
        !           363:                 */
        !           364:                fp->fp_mant[0] |= FP_QUIETBIT;
        !           365:                fe->fe_fpsr |= FPSR_SNAN;       /* assert SNAN exception */
        !           366:                s = FPC_SNAN;
        !           367:        }
        !           368:        fp->fp_class = s;
        !           369: }

This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.