ADR_IMM_HILOSPLIT
imm >>= ADR_IMM_HILOSPLIT;
#define ADR_IMM_LOMASK ((1 << ADR_IMM_HILOSPLIT) - 1)
#define ADR_IMM_HIMASK ((ADR_IMM_SIZE >> ADR_IMM_HILOSPLIT) - 1)
insn = (immhi << ADR_IMM_HILOSPLIT) | immlo;