QEMU decodetree example

decodetree.c

/* This file is autogenerated by scripts/decodetree.py.  */

typedef struct {
    int reg0;
    int reg1;
    int imm16;
} arg_ri;

typedef arg_ri arg_addi;
static bool trans_addi(DisasContext *ctx, arg_addi *a);

static void decode_extract_ri(DisasContext *ctx, arg_ri *a, uint32_t insn) {
    a->reg1  = extract32(insn, 16, 5);
    a->reg0  = extract32(insn, 21, 5);
    a->imm16 = extract32(insn, 0, 16);
}

static bool decode(DisasContext *ctx, uint32_t insn) {
    union {
        arg_ri f_ri;
    } u;

    decode_extract_ri(ctx, &u.f_ri, insn);
    switch ((insn >> 26) & 0x3f) {
    case 0xd:
        /* 001101.. ........ ........ ........ */
        /* target/lm32/insns.decode:28 */
        if (trans_addi(ctx, &u.f_ri))
            return true;
        break;
    }
    return false;
}

insns.decode

# Fields:
%reg0 21:5
%reg1 16:5

# Immediates:
%imm16 0:16

# Argument sets:
&ri reg0 reg1 imm16

# Formats:
@ri  . ..... ..... ..... ................ &ri %reg0 %reg1 %imm16

# Instructions:
addi 0 01101 ..... ..... ................ @ri