#if not(ARCH_6502)
#warn zp_reg module should be used only on 6502-compatible targets
#endif

inline asm byte __mul_u8u8u8() {
    ? LDA #0
    ? JMP __mul_u8u8u8_start
__mul_u8u8u8_add:
    ? CLC
    ? ADC __reg.lo
__mul_u8u8u8_loop:
    ? ASL __reg.lo
__mul_u8u8u8_start:
    ? LSR __reg.hi
    ? BCS __mul_u8u8u8_add
    ? BNE __mul_u8u8u8_loop
    ? RTS
}