.text
        .global mul64p
mul64p: // (a(12), b(8)) * (c(20), d(16))
        pushl   %ebp
        movl    %esp, %ebp
        xorl    %eax, %eax
        subl    $16, %esp
        movl    $0, (%esp)
        movl    $0, 4(%esp)
        movl    $0, 8(%esp)
        movl    $0, 12(%esp)

        // d * b
        movl    8(%ebp), %eax
        mull    16(%ebp)
        movl    %eax, (%esp)
        movl    %edx, 4(%esp)

        //  a * d
        movl    12(%ebp), %eax
        mull    16(%ebp)
        addl    %eax, 4(%esp)
        adcl    %edx, 8(%esp)
        adcl    $0, 12(%esp)

        //  c * b
        movl    8(%ebp), %eax
        mull    20(%ebp)
        addl    %eax, 4(%esp)
        adcl    %edx, 8(%esp)
        adcl    $0, 12(%esp)

        //  a * c
        movl    12(%ebp), %eax
        mull    20(%ebp)
        addl    %eax, 8(%esp)
        adcl    %edx, 12(%esp)

        //  write number
        //  first
        xorl    %ebx, %ebx
        movl    12(%esp), %eax
        testl   %eax, %eax
        jz      f2
        movl    $1, %ebx
        pushl   %eax
        pushl   $fout
        call    printf
        addl    $8, %esp
        jmp     n2

f2:     movl    8(%esp), %eax
        testl   %eax, %eax
        jz      f3
        pushl   %eax
        pushl   $fout
        call    printf
        addl    $8, %esp
        jmp     n3

f3:     movl    4(%esp), %eax
        testl   %eax, %eax
        jz      f4
        pushl   %eax
        pushl   $fout
        call    printf
        addl    $8, %esp
        jmp     n4

f4:     pushl   $fout
        call    printf
        addl    $4, %esp
        jmp     end

n2:     movl    8(%esp), %eax
        pushl   %eax
        pushl   $nout
        call    printf
        addl    $8, %esp

n3:     movl    4(%esp), %eax
        pushl   %eax
        pushl   $nout
        call    printf
        addl    $8, %esp

n4:     pushl   $nout
        call    printf
        addl    $4, %esp

end:    pushl   $nl
        call    printf
        addl    $20, %esp
        popl    %ebp
        ret


        .data
zero:   .quad   0x0
fout:   .asciz  "%x"
nout:   .asciz  "%08x"
nl:     .asciz  "\n"