Commit 67b453ed authored by Laurent Vivier's avatar Laurent Vivier
Browse files

target/m68k: implement flog2 



Using a local m68k floatx80_log2()
[copied from previous:
Written by Andreas Grabher for Previous, NeXT Computer Emulator.]

Signed-off-by: default avatarLaurent Vivier <laurent@vivier.eu>
Message-Id: <20180305203910.10391-6-laurent@vivier.eu>
parent 248efb66

target/m68k/fpu_helper.c

+5 −0
Original line number Diff line number Diff line
@@ -572,3 +572,8 @@ void HELPER(flog10)(CPUM68KState *env, FPReg *res, FPReg *val) 
{

    res->d = floatx80_log10(val->d, &env->fp_status);

}



void HELPER(flog2)(CPUM68KState *env, FPReg *res, FPReg *val)

{

    res->d = floatx80_log2(val->d, &env->fp_status);

}

target/m68k/helper.h

+1 −0
Original line number Diff line number Diff line
@@ -71,6 +71,7 @@ DEF_HELPER_4(fscale, void, env, fp, fp, fp) 
DEF_HELPER_3(flognp1, void, env, fp, fp)

DEF_HELPER_3(flogn, void, env, fp, fp)

DEF_HELPER_3(flog10, void, env, fp, fp)

DEF_HELPER_3(flog2, void, env, fp, fp)



DEF_HELPER_3(mac_move, void, env, i32, i32)

DEF_HELPER_3(macmulf, i64, env, i32, i32)

target/m68k/softfloat.c

+67 −0
Original line number Diff line number Diff line
@@ -715,3 +715,70 @@ floatx80 floatx80_log10(floatx80 a, float_status *status) 


    return a;

}



/*----------------------------------------------------------------------------

 | Log base 2

 *----------------------------------------------------------------------------*/



floatx80 floatx80_log2(floatx80 a, float_status *status)

{

    flag aSign;

    int32_t aExp;

    uint64_t aSig;



    int8_t user_rnd_mode, user_rnd_prec;



    floatx80 fp0, fp1;



    aSig = extractFloatx80Frac(a);

    aExp = extractFloatx80Exp(a);

    aSign = extractFloatx80Sign(a);



    if (aExp == 0x7FFF) {

        if ((uint64_t) (aSig << 1)) {

            propagateFloatx80NaNOneArg(a, status);

        }

        if (aSign == 0) {

            return packFloatx80(0, floatx80_infinity.high,

                                floatx80_infinity.low);

        }

    }



    if (aExp == 0) {

        if (aSig == 0) {

            float_raise(float_flag_divbyzero, status);

            return packFloatx80(1, floatx80_infinity.high,

                                floatx80_infinity.low);

        }

        normalizeFloatx80Subnormal(aSig, &aExp, &aSig);

    }



    if (aSign) {

        float_raise(float_flag_invalid, status);

        return floatx80_default_nan(status);

    }



    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;



    if (aSig == one_sig) { /* X is 2^k */

        status->float_rounding_mode = user_rnd_mode;

        status->floatx80_rounding_precision = user_rnd_prec;



        a = int32_to_floatx80(aExp - 0x3FFF, status);

    } else {

        fp0 = floatx80_logn(a, status);

        fp1 = packFloatx80(0, 0x3FFF, LIT64(0xB8AA3B295C17F0BC)); /* INV_L2 */



        status->float_rounding_mode = user_rnd_mode;

        status->floatx80_rounding_precision = user_rnd_prec;



        a = floatx80_mul(fp0, fp1, status); /* LOGN(X)*INV_L2 */

    }



    float_raise(float_flag_inexact, status);



    return a;

}

target/m68k/softfloat.h

+1 −0
Original line number Diff line number Diff line
@@ -30,4 +30,5 @@ floatx80 floatx80_move(floatx80 a, float_status *status); 
floatx80 floatx80_lognp1(floatx80 a, float_status *status);

floatx80 floatx80_logn(floatx80 a, float_status *status);

floatx80 floatx80_log10(floatx80 a, float_status *status);

floatx80 floatx80_log2(floatx80 a, float_status *status);

#endif

target/m68k/translate.c

+3 −0
Original line number Diff line number Diff line
@@ -5063,6 +5063,9 @@ DISAS_INSN(fpu) 
    case 0x15: /* flog10 */

        gen_helper_flog10(cpu_env, cpu_dest, cpu_src);

        break;

    case 0x16: /* flog2 */

        gen_helper_flog2(cpu_env, cpu_dest, cpu_src);

        break;

    case 0x18: /* fabs */

        gen_helper_fabs(cpu_env, cpu_dest, cpu_src);

        break;