Archipelago » qemu

/* C3.4.2 Bitfield

 *   31  30 29 28         23 22  21  16 15  10 9    5 4    0

 * +----+-----+-------------+---+------+------+------+------+

 * | sf | opc | 1 0 0 1 1 0 | N | immr | imms |  Rn  |  Rd  |

 * +----+-----+-------------+---+------+------+------+------+

 */

    unsigned int sf, n, opc, ri, si, rn, rd, bitsize, pos, len;

    TCGv_i64 tcg_rd, tcg_tmp;

    sf = extract32(insn, 31, 1);

    opc = extract32(insn, 29, 2);

    n = extract32(insn, 22, 1);

    ri = extract32(insn, 16, 6);

    si = extract32(insn, 10, 6);

    rn = extract32(insn, 5, 5);

    rd = extract32(insn, 0, 5);

    bitsize = sf ? 64 : 32;

    if (sf != n || ri >= bitsize || si >= bitsize || opc > 2) {

        unallocated_encoding(s);

        return;

    }

    tcg_rd = cpu_reg(s, rd);

    tcg_tmp = read_cpu_reg(s, rn, sf);

    /* OPTME: probably worth recognizing common cases of ext{8,16,32}{u,s} */

    if (opc != 1) { /* SBFM or UBFM */

        tcg_gen_movi_i64(tcg_rd, 0);

    }

    /* do the bit move operation */

    if (si >= ri) {

        /* Wd<s-r:0> = Wn<s:r> */

        tcg_gen_shri_i64(tcg_tmp, tcg_tmp, ri);

        pos = 0;

        len = (si - ri) + 1;

    } else {

        /* Wd<32+s-r,32-r> = Wn<s:0> */

        pos = bitsize - ri;

        len = si + 1;

    }

    tcg_gen_deposit_i64(tcg_rd, tcg_rd, tcg_tmp, pos, len);

    if (opc == 0) { /* SBFM - sign extend the destination field */

        tcg_gen_shli_i64(tcg_rd, tcg_rd, 64 - (pos + len));

        tcg_gen_sari_i64(tcg_rd, tcg_rd, 64 - (pos + len));

    }

    if (!sf) { /* zero extend final result */

        tcg_gen_ext32u_i64(tcg_rd, tcg_rd);

    }