Revision 5e9ae189 target-ppc/op_helper.c

b/target-ppc/op_helper.c
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/* 602 specific instructions */
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/* mfrom is the most crazy instruction ever seen, imho ! */
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/* Real implementation uses a ROM table. Do the same */
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/* Extremly decomposed:
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 *                      -arg / 256
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 * return 256 * log10(10           + 1.0) + 0.5
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 */
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#if !defined (CONFIG_USER_ONLY)
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#define USE_MFROM_ROM_TABLE
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target_ulong helper_602_mfrom (target_ulong arg)
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{
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    if (likely(arg < 602)) {
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#if defined(USE_MFROM_ROM_TABLE)
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#include "mfrom_table.c"
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        return mfrom_ROM_table[arg];
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#else
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        double d;
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        /* Extremly decomposed:
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         *                      -arg / 256
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         * return 256 * log10(10           + 1.0) + 0.5
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         */
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        d = arg;
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        d = float64_div(d, 256, &env->fp_status);
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        d = float64_chs(d);
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        d = exp10(d); // XXX: use float emulation function
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        d = float64_add(d, 1.0, &env->fp_status);
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        d = log10(d); // XXX: use float emulation function
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        d = float64_mul(d, 256, &env->fp_status);
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        d = float64_add(d, 0.5, &env->fp_status);
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        return float64_round_to_int(d, &env->fp_status);
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#endif
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    } else {
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        return 0;
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    }

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