target/m68k: implement flognp1
Using a local m68k floatx80_lognp1() [copied from previous: Written by Andreas Grabher for Previous, NeXT Computer Emulator.] Signed-off-by: Laurent Vivier <laurent@vivier.eu> Message-Id: <20180305203910.10391-3-laurent@vivier.eu>
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@@ -21,6 +21,7 @@
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#include "qemu/osdep.h"
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#include "softfloat.h"
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#include "fpu/softfloat-macros.h"
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#include "softfloat_fpsp_tables.h"
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static floatx80 propagateFloatx80NaNOneArg(floatx80 a, float_status *status)
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{
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@@ -274,3 +275,218 @@ floatx80 floatx80_move(floatx80 a, float_status *status)
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return roundAndPackFloatx80(status->floatx80_rounding_precision, aSign,
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aExp, aSig, 0, status);
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}
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/*----------------------------------------------------------------------------
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| Algorithms for transcendental functions supported by MC68881 and MC68882
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| mathematical coprocessors. The functions are derived from FPSP library.
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*----------------------------------------------------------------------------*/
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#define one_exp 0x3FFF
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#define one_sig LIT64(0x8000000000000000)
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/*----------------------------------------------------------------------------
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| Function for compactifying extended double-precision floating point values.
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*----------------------------------------------------------------------------*/
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static int32_t floatx80_make_compact(int32_t aExp, uint64_t aSig)
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{
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return (aExp << 16) | (aSig >> 48);
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}
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/*----------------------------------------------------------------------------
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| Log base e of x plus 1
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*----------------------------------------------------------------------------*/
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floatx80 floatx80_lognp1(floatx80 a, float_status *status)
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{
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flag aSign;
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int32_t aExp;
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uint64_t aSig, fSig;
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int8_t user_rnd_mode, user_rnd_prec;
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int32_t compact, j, k;
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floatx80 fp0, fp1, fp2, fp3, f, logof2, klog2, saveu;
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aSig = extractFloatx80Frac(a);
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aExp = extractFloatx80Exp(a);
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aSign = extractFloatx80Sign(a);
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if (aExp == 0x7FFF) {
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if ((uint64_t) (aSig << 1)) {
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propagateFloatx80NaNOneArg(a, status);
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}
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if (aSign) {
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float_raise(float_flag_invalid, status);
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return floatx80_default_nan(status);
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}
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return packFloatx80(0, floatx80_infinity.high, floatx80_infinity.low);
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}
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if (aExp == 0 && aSig == 0) {
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return packFloatx80(aSign, 0, 0);
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}
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if (aSign && aExp >= one_exp) {
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if (aExp == one_exp && aSig == one_sig) {
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float_raise(float_flag_divbyzero, status);
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packFloatx80(aSign, floatx80_infinity.high, floatx80_infinity.low);
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}
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float_raise(float_flag_invalid, status);
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return floatx80_default_nan(status);
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}
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if (aExp < 0x3f99 || (aExp == 0x3f99 && aSig == one_sig)) {
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/* <= min threshold */
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float_raise(float_flag_inexact, status);
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return floatx80_move(a, status);
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}
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user_rnd_mode = status->float_rounding_mode;
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user_rnd_prec = status->floatx80_rounding_precision;
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status->float_rounding_mode = float_round_nearest_even;
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status->floatx80_rounding_precision = 80;
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compact = floatx80_make_compact(aExp, aSig);
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fp0 = a; /* Z */
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fp1 = a;
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fp0 = floatx80_add(fp0, float32_to_floatx80(make_float32(0x3F800000),
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status), status); /* X = (1+Z) */
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aExp = extractFloatx80Exp(fp0);
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aSig = extractFloatx80Frac(fp0);
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compact = floatx80_make_compact(aExp, aSig);
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if (compact < 0x3FFE8000 || compact > 0x3FFFC000) {
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/* |X| < 1/2 or |X| > 3/2 */
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k = aExp - 0x3FFF;
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fp1 = int32_to_floatx80(k, status);
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fSig = (aSig & LIT64(0xFE00000000000000)) | LIT64(0x0100000000000000);
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j = (fSig >> 56) & 0x7E; /* DISPLACEMENT FOR 1/F */
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f = packFloatx80(0, 0x3FFF, fSig); /* F */
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fp0 = packFloatx80(0, 0x3FFF, aSig); /* Y */
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fp0 = floatx80_sub(fp0, f, status); /* Y-F */
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lp1cont1:
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/* LP1CONT1 */
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fp0 = floatx80_mul(fp0, log_tbl[j], status); /* FP0 IS U = (Y-F)/F */
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logof2 = packFloatx80(0, 0x3FFE, LIT64(0xB17217F7D1CF79AC));
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klog2 = floatx80_mul(fp1, logof2, status); /* FP1 IS K*LOG2 */
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fp2 = floatx80_mul(fp0, fp0, status); /* FP2 IS V=U*U */
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fp3 = fp2;
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fp1 = fp2;
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fp1 = floatx80_mul(fp1, float64_to_floatx80(
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make_float64(0x3FC2499AB5E4040B), status),
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status); /* V*A6 */
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fp2 = floatx80_mul(fp2, float64_to_floatx80(
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make_float64(0xBFC555B5848CB7DB), status),
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status); /* V*A5 */
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fp1 = floatx80_add(fp1, float64_to_floatx80(
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make_float64(0x3FC99999987D8730), status),
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status); /* A4+V*A6 */
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fp2 = floatx80_add(fp2, float64_to_floatx80(
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make_float64(0xBFCFFFFFFF6F7E97), status),
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status); /* A3+V*A5 */
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fp1 = floatx80_mul(fp1, fp3, status); /* V*(A4+V*A6) */
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fp2 = floatx80_mul(fp2, fp3, status); /* V*(A3+V*A5) */
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fp1 = floatx80_add(fp1, float64_to_floatx80(
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make_float64(0x3FD55555555555A4), status),
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status); /* A2+V*(A4+V*A6) */
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fp2 = floatx80_add(fp2, float64_to_floatx80(
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make_float64(0xBFE0000000000008), status),
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status); /* A1+V*(A3+V*A5) */
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fp1 = floatx80_mul(fp1, fp3, status); /* V*(A2+V*(A4+V*A6)) */
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fp2 = floatx80_mul(fp2, fp3, status); /* V*(A1+V*(A3+V*A5)) */
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fp1 = floatx80_mul(fp1, fp0, status); /* U*V*(A2+V*(A4+V*A6)) */
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fp0 = floatx80_add(fp0, fp2, status); /* U+V*(A1+V*(A3+V*A5)) */
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fp1 = floatx80_add(fp1, log_tbl[j + 1],
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status); /* LOG(F)+U*V*(A2+V*(A4+V*A6)) */
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fp0 = floatx80_add(fp0, fp1, status); /* FP0 IS LOG(F) + LOG(1+U) */
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status->float_rounding_mode = user_rnd_mode;
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status->floatx80_rounding_precision = user_rnd_prec;
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a = floatx80_add(fp0, klog2, status);
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float_raise(float_flag_inexact, status);
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return a;
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} else if (compact < 0x3FFEF07D || compact > 0x3FFF8841) {
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/* |X| < 1/16 or |X| > -1/16 */
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/* LP1CARE */
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fSig = (aSig & LIT64(0xFE00000000000000)) | LIT64(0x0100000000000000);
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f = packFloatx80(0, 0x3FFF, fSig); /* F */
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j = (fSig >> 56) & 0x7E; /* DISPLACEMENT FOR 1/F */
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if (compact >= 0x3FFF8000) { /* 1+Z >= 1 */
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/* KISZERO */
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fp0 = floatx80_sub(float32_to_floatx80(make_float32(0x3F800000),
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status), f, status); /* 1-F */
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fp0 = floatx80_add(fp0, fp1, status); /* FP0 IS Y-F = (1-F)+Z */
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fp1 = packFloatx80(0, 0, 0); /* K = 0 */
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} else {
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/* KISNEG */
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fp0 = floatx80_sub(float32_to_floatx80(make_float32(0x40000000),
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status), f, status); /* 2-F */
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fp1 = floatx80_add(fp1, fp1, status); /* 2Z */
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fp0 = floatx80_add(fp0, fp1, status); /* FP0 IS Y-F = (2-F)+2Z */
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fp1 = packFloatx80(1, one_exp, one_sig); /* K = -1 */
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}
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goto lp1cont1;
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} else {
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/* LP1ONE16 */
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fp1 = floatx80_add(fp1, fp1, status); /* FP1 IS 2Z */
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fp0 = floatx80_add(fp0, float32_to_floatx80(make_float32(0x3F800000),
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status), status); /* FP0 IS 1+X */
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/* LP1CONT2 */
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fp1 = floatx80_div(fp1, fp0, status); /* U */
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saveu = fp1;
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fp0 = floatx80_mul(fp1, fp1, status); /* FP0 IS V = U*U */
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fp1 = floatx80_mul(fp0, fp0, status); /* FP1 IS W = V*V */
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fp3 = float64_to_floatx80(make_float64(0x3F175496ADD7DAD6),
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status); /* B5 */
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fp2 = float64_to_floatx80(make_float64(0x3F3C71C2FE80C7E0),
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status); /* B4 */
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fp3 = floatx80_mul(fp3, fp1, status); /* W*B5 */
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fp2 = floatx80_mul(fp2, fp1, status); /* W*B4 */
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fp3 = floatx80_add(fp3, float64_to_floatx80(
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make_float64(0x3F624924928BCCFF), status),
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status); /* B3+W*B5 */
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fp2 = floatx80_add(fp2, float64_to_floatx80(
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make_float64(0x3F899999999995EC), status),
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status); /* B2+W*B4 */
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fp1 = floatx80_mul(fp1, fp3, status); /* W*(B3+W*B5) */
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fp2 = floatx80_mul(fp2, fp0, status); /* V*(B2+W*B4) */
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fp1 = floatx80_add(fp1, float64_to_floatx80(
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make_float64(0x3FB5555555555555), status),
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status); /* B1+W*(B3+W*B5) */
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fp0 = floatx80_mul(fp0, saveu, status); /* FP0 IS U*V */
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fp1 = floatx80_add(fp1, fp2,
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status); /* B1+W*(B3+W*B5) + V*(B2+W*B4) */
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fp0 = floatx80_mul(fp0, fp1,
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status); /* U*V*([B1+W*(B3+W*B5)] + [V*(B2+W*B4)]) */
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status->float_rounding_mode = user_rnd_mode;
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status->floatx80_rounding_precision = user_rnd_prec;
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a = floatx80_add(fp0, saveu, status);
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/*if (!floatx80_is_zero(a)) { */
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float_raise(float_flag_inexact, status);
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/*} */
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return a;
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}
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}
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