libmwemu 0.25.1

x86 32/64bits and system internals emulator, for securely emulating malware and other stuff.
Documentation 
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use crate::color;
use crate::emu::Emu;
use iced_x86::Instruction;

// BLSMSK dest, src: dest = (src - 1) XOR src  (mask up to & including lowest set bit)
pub fn execute(emu: &mut Emu, ins: &Instruction, _instruction_sz: usize, _rep_step: bool) -> bool {
    emu.show_instruction(color!("Green"), &crate::emu::decoded_instruction::DecodedInstruction::X86(*ins));

    let src = match emu.get_operand_value(ins, 1, true) {
        Some(v) => v,
        None => return false,
    };

    let sz = emu.get_operand_sz(ins, 0);
    let mask: u64 = if sz >= 64 { u64::MAX } else { (1u64 << sz) - 1 };
    let result = (src.wrapping_sub(1) ^ src) & mask;

    // CF set when source is zero; OF cleared; SF/ZF reflect the result.
    emu.flags_mut().f_cf = src == 0;
    emu.flags_mut().f_of = false;
    emu.flags_mut().f_zf = result == 0;
    emu.flags_mut().f_sf = (result >> (sz - 1)) & 1 == 1;

    emu.set_operand_value(ins, 0, result);
    true
}