mul64.s

ARM源码

        AREA ARMex, CODE, READONLY  ; name this block of code
        ENTRY                       ; mark first instruction
                                ; to execute

start
    MOV    ip, a1, LSR #16        ; ip = a_hi
    MOV    a4, a2, LSR #16        ; a4 = b_hi
    BIC    a1, a1, ip, LSL #16    ; a1 = a_lo
    BIC    a2, a2, a4, LSL #16    ; a2 = b_lo
    MUL    a3, a1, a2             ; a3 = a_lo * b_lo        (m_lo)
    MUL    a2, ip, a2             ; a2 = a_hi * b_lo        (m_mid1)
    MUL    a1, a4, a1             ; a1 = a_lo * b_hi        (m_mid2)
    MUL    a4, ip, a4             ; a4 = a_hi * b_hi        (m_hi)
    ADDS   ip, a2, a1             ; ip = m_mid1 + m_mid2    (m_mid)
    ADDCS  a4, a4, #&10000        ; a4 = m_hi + carry       (m_hi')
    ADDS   a1, a3, ip, LSL #16    ; a1 = m_lo + (m_mid<<16)
    ADC    a2, a4, ip, LSR #16    ; a2 = m_hi' + (m_mid>>16) + carry
    MOV    pc, lr

stop
        MOV     r0, #0x18           ; angel_SWIreason_ReportException
        LDR     r1, =0x20026        ; ADP_Stopped_ApplicationExit
        SWI     0x123456            ; Angel semihosting ARM SWI

        END                         ; Mark end of file