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target/m68k: implement ftentox

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Using a local m68k floatx80_tentox()
[copied from previous:
Written by Andreas Grabher for Previous, NeXT Computer Emulator.]

Backports commit 6c25be6e30bda0e470f8f0b6b93d53a6efe469e8 from qemu
This commit is contained in:
Laurent Vivier 2018-03-12 09:36:22 -04:00 committed by Lioncash
parent 61fa8cf539
commit 418f96df9b
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GPG Key ID: 4E3C3CC1031BA9C7
5 changed files with 163 additions and 0 deletions
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5
qemu/target/m68k/fpu_helper.c
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@ -598,3 +598,8 @@ void HELPER(ftwotox)(CPUM68KState *env, FPReg *res, FPReg *val)
{
res->d = floatx80_twotox(val->d, &env->fp_status);
}
void HELPER(ftentox)(CPUM68KState *env, FPReg *res, FPReg *val)
{
res->d = floatx80_tentox(val->d, &env->fp_status);
}

1
qemu/target/m68k/helper.h
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@ -75,6 +75,7 @@ DEF_HELPER_3(flog10, void, env, fp, fp)
DEF_HELPER_3(flog2, void, env, fp, fp)
DEF_HELPER_3(fetox, void, env, fp, fp)
DEF_HELPER_3(ftwotox, void, env, fp, fp)
DEF_HELPER_3(ftentox, void, env, fp, fp)
DEF_HELPER_3(mac_move, void, env, i32, i32)
DEF_HELPER_3(macmulf, i64, env, i32, i32)

153
qemu/target/m68k/softfloat.c
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@ -1113,3 +1113,156 @@ floatx80 floatx80_twotox(floatx80 a, float_status *status)
return a;
}
}
/*----------------------------------------------------------------------------
| 10 to x
*----------------------------------------------------------------------------*/
floatx80 floatx80_tentox(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 > 0x400B9B07) {
/* |X| > 16480 LOG2/LOG10 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 LOG 2 / LOG 10 */
fp1 = fp0; /* X */
fp1 = floatx80_mul(fp1, float64_to_floatx80(
make_float64(0x406A934F0979A371),
status), status); /* X*64*LOG10/LOG2 */
n = floatx80_to_int32(fp1, status); /* N=INT(X*64*LOG10/LOG2) */
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;
fp2 = fp1; /* N */
fp1 = floatx80_mul(fp1, float64_to_floatx80(
make_float64(0x3F734413509F8000), status),
status); /* N*(LOG2/64LOG10)_LEAD */
fp3 = packFloatx80(1, 0x3FCD, LIT64(0xC0219DC1DA994FD2));
fp2 = floatx80_mul(fp2, fp3, status); /* N*(LOG2/64LOG10)_TRAIL */
fp0 = floatx80_sub(fp0, fp1, status); /* X - N L_LEAD */
fp0 = floatx80_sub(fp0, fp2, status); /* X - N L_TRAIL */
fp2 = packFloatx80(0, 0x4000, LIT64(0x935D8DDDAAA8AC17)); /* LOG10 */
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;
}
}

1
qemu/target/m68k/softfloat.h
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@ -33,4 +33,5 @@ floatx80 floatx80_log10(floatx80 a, float_status *status);
floatx80 floatx80_log2(floatx80 a, float_status *status);
floatx80 floatx80_etox(floatx80 a, float_status *status);
floatx80 floatx80_twotox(floatx80 a, float_status *status);
floatx80 floatx80_tentox(floatx80 a, float_status *status);
#endif

3
qemu/target/m68k/translate.c
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@ -5262,6 +5262,9 @@ DISAS_INSN(fpu)
case 0x11: /* ftwotox */
gen_helper_ftwotox(tcg_ctx, tcg_ctx->cpu_env, cpu_dest, cpu_src);
break;
case 0x12: /* ftentox */
gen_helper_ftentox(tcg_ctx, tcg_ctx->cpu_env, cpu_dest, cpu_src);
break;
case 0x14: /* flogn */
gen_helper_flogn(tcg_ctx, tcg_ctx->cpu_env, cpu_dest, cpu_src);
break;