diff options
Diffstat (limited to 'target/m68k/softfloat.c')
| -rw-r--r-- | target/m68k/softfloat.c | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/target/m68k/softfloat.c b/target/m68k/softfloat.c index e58eb91..cfff30d 100644 --- a/target/m68k/softfloat.c +++ b/target/m68k/softfloat.c @@ -965,3 +965,151 @@ floatx80 floatx80_etox(floatx80 a, float_status *status) return a; } } + +/*---------------------------------------------------------------------------- + | 2 to x + *----------------------------------------------------------------------------*/ + +floatx80 floatx80_twotox(floatx80 a, float_status *status) +{ + flag aSign; + int32_t aExp; + uint64_t aSig; + + int8_t user_rnd_mode, user_rnd_prec; + + int32_t compact, n, j, l, m, m1; + floatx80 fp0, fp1, fp2, fp3, adjfact, fact1, fact2; + + aSig = extractFloatx80Frac(a); + aExp = extractFloatx80Exp(a); + aSign = extractFloatx80Sign(a); + + if (aExp == 0x7FFF) { + if ((uint64_t) (aSig << 1)) { + return propagateFloatx80NaNOneArg(a, status); + } + if (aSign) { + return packFloatx80(0, 0, 0); + } + return packFloatx80(0, floatx80_infinity.high, + floatx80_infinity.low); + } + + if (aExp == 0 && aSig == 0) { + return packFloatx80(0, one_exp, one_sig); + } + + user_rnd_mode = status->float_rounding_mode; + user_rnd_prec = status->floatx80_rounding_precision; + status->float_rounding_mode = float_round_nearest_even; + status->floatx80_rounding_precision = 80; + + fp0 = a; + + compact = floatx80_make_compact(aExp, aSig); + + if (compact < 0x3FB98000 || compact > 0x400D80C0) { + /* |X| > 16480 or |X| < 2^(-70) */ + if (compact > 0x3FFF8000) { /* |X| > 16480 */ + status->float_rounding_mode = user_rnd_mode; + status->floatx80_rounding_precision = user_rnd_prec; + + if (aSign) { + return roundAndPackFloatx80(status->floatx80_rounding_precision, + 0, -0x1000, aSig, 0, status); + } else { + return roundAndPackFloatx80(status->floatx80_rounding_precision, + 0, 0x8000, aSig, 0, status); + } + } else { /* |X| < 2^(-70) */ + status->float_rounding_mode = user_rnd_mode; + status->floatx80_rounding_precision = user_rnd_prec; + + a = floatx80_add(fp0, float32_to_floatx80( + make_float32(0x3F800000), status), + status); /* 1 + X */ + + float_raise(float_flag_inexact, status); + + return a; + } + } else { /* 2^(-70) <= |X| <= 16480 */ + fp1 = fp0; /* X */ + fp1 = floatx80_mul(fp1, float32_to_floatx80( + make_float32(0x42800000), status), + status); /* X * 64 */ + n = floatx80_to_int32(fp1, status); + fp1 = int32_to_floatx80(n, status); + j = n & 0x3F; + l = n / 64; /* NOTE: this is really arithmetic right shift by 6 */ + if (n < 0 && j) { + /* arithmetic right shift is division and + * round towards minus infinity + */ + l--; + } + m = l / 2; /* NOTE: this is really arithmetic right shift by 1 */ + if (l < 0 && (l & 1)) { + /* arithmetic right shift is division and + * round towards minus infinity + */ + m--; + } + m1 = l - m; + m1 += 0x3FFF; /* ADJFACT IS 2^(M') */ + + adjfact = packFloatx80(0, m1, one_sig); + fact1 = exp2_tbl[j]; + fact1.high += m; + fact2.high = exp2_tbl2[j] >> 16; + fact2.high += m; + fact2.low = (uint64_t)(exp2_tbl2[j] & 0xFFFF); + fact2.low <<= 48; + + fp1 = floatx80_mul(fp1, float32_to_floatx80( + make_float32(0x3C800000), status), + status); /* (1/64)*N */ + fp0 = floatx80_sub(fp0, fp1, status); /* X - (1/64)*INT(64 X) */ + fp2 = packFloatx80(0, 0x3FFE, LIT64(0xB17217F7D1CF79AC)); /* LOG2 */ + fp0 = floatx80_mul(fp0, fp2, status); /* R */ + + /* EXPR */ + fp1 = floatx80_mul(fp0, fp0, status); /* S = R*R */ + fp2 = float64_to_floatx80(make_float64(0x3F56C16D6F7BD0B2), + status); /* A5 */ + fp3 = float64_to_floatx80(make_float64(0x3F811112302C712C), + status); /* A4 */ + fp2 = floatx80_mul(fp2, fp1, status); /* S*A5 */ + fp3 = floatx80_mul(fp3, fp1, status); /* S*A4 */ + fp2 = floatx80_add(fp2, float64_to_floatx80( + make_float64(0x3FA5555555554CC1), status), + status); /* A3+S*A5 */ + fp3 = floatx80_add(fp3, float64_to_floatx80( + make_float64(0x3FC5555555554A54), status), + status); /* A2+S*A4 */ + fp2 = floatx80_mul(fp2, fp1, status); /* S*(A3+S*A5) */ + fp3 = floatx80_mul(fp3, fp1, status); /* S*(A2+S*A4) */ + fp2 = floatx80_add(fp2, float64_to_floatx80( + make_float64(0x3FE0000000000000), status), + status); /* A1+S*(A3+S*A5) */ + fp3 = floatx80_mul(fp3, fp0, status); /* R*S*(A2+S*A4) */ + + fp2 = floatx80_mul(fp2, fp1, status); /* S*(A1+S*(A3+S*A5)) */ + fp0 = floatx80_add(fp0, fp3, status); /* R+R*S*(A2+S*A4) */ + fp0 = floatx80_add(fp0, fp2, status); /* EXP(R) - 1 */ + + fp0 = floatx80_mul(fp0, fact1, status); + fp0 = floatx80_add(fp0, fact2, status); + fp0 = floatx80_add(fp0, fact1, status); + + status->float_rounding_mode = user_rnd_mode; + status->floatx80_rounding_precision = user_rnd_prec; + + a = floatx80_mul(fp0, adjfact, status); + + float_raise(float_flag_inexact, status); + + return a; + } +} |