求达人解释这段汇编

allan1109 2012-02-16 07:09:16

小弟刚学汇编。只能看懂一些基本的操作。下面这段里面涉及好多没见过的操作符，望达人指教给我解释下整个的意思。因为转成c其实是一段很简单的代码。

Dump of assembler code for function main:

   0x0804843b <+0>:     push   %ebp

   0x0804843c <+1>:     mov    %esp,%ebp

   0x0804843e <+3>:     and    $0xfffffff0,%esp

   0x08048441 <+6>:     sub    $0x30,%esp

   0x08048444 <+9>:     movl   $0x3,0x2c(%esp)

   0x0804844c <+17>:    movl   $0x6,0x28(%esp)

   0x08048454 <+25>:    mov    $0x3f99999a,%eax

   0x08048459 <+30>:    mov    %eax,0x20(%esp)

   0x0804845d <+34>:    fildl  0x2c(%esp)

   0x08048461 <+38>:    flds   0x804a014

   0x08048467 <+44>:    fmulp  %st,%st(1)

   0x08048469 <+46>:    fnstcw 0x1e(%esp)

   0x0804846d <+50>:    movzwl 0x1e(%esp),%eax

   0x08048472 <+55>:    mov    $0xc,%ah

   0x08048474 <+57>:    mov    %ax,0x1c(%esp)

   0x08048479 <+62>:    fldcw  0x1c(%esp)

   0x0804847d <+66>:    fistpl 0x18(%esp)

   0x08048481 <+70>:    fldcw  0x1e(%esp)

   0x08048485 <+74>:    mov    0x18(%esp),%eax

   0x08048489 <+78>:    mov    0x28(%esp),%edx

   0x0804848d <+82>:    mov    %edx,0x4(%esp)

   0x08048491 <+86>:    mov    %eax,(%esp)

   0x08048494 <+89>:    call   0x804841b <bar>

   0x08048499 <+94>:    mov    %eax,0x24(%esp)

   0x0804849d <+98>:    mov    $0x8048580,%eax

   0x080484a2 <+103>:   mov    0x24(%esp),%edx

   0x080484a6 <+107>:   mov    %edx,0x4(%esp)

   0x080484aa <+111>:   mov    %eax,(%esp)

   0x080484ad <+114>:   call   0x804831c <printf@plt>

   0x080484b2 <+119>:   mov    $0x0,%eax

   0x080484b7 <+124>:   leave  

   0x080484b8 <+125>:   ret    

End of assembler dump.

Dump of assembler code for function foo:

   0x080483e4 <+0>:     push   %ebp

   0x080483e5 <+1>:     mov    %esp,%ebp

   0x080483e7 <+3>:     sub    $0x18,%esp

   0x080483ea <+6>:     mov    0x8(%ebp),%edx

   0x080483ed <+9>:     mov    %edx,%eax

   0x080483ef <+11>:    shl    $0x2,%eax

   0x080483f2 <+14>:    add    %edx,%eax

   0x080483f4 <+16>:    mov    %eax,-0x14(%ebp)

   0x080483f7 <+19>:    fildl  -0x14(%ebp)

   0x080483fa <+22>:    fstpl  -0x8(%ebp)

   0x080483fd <+25>:    fldl   -0x8(%ebp)

   0x08048400 <+28>:    fnstcw -0x16(%ebp)

   0x08048403 <+31>:    movzwl -0x16(%ebp),%eax

   0x08048407 <+35>:    mov    $0xc,%ah

   0x08048409 <+37>:    mov    %ax,-0x18(%ebp)

   0x0804840d <+41>:    fldcw  -0x18(%ebp)

   0x08048410 <+44>:    fistpl -0x14(%ebp)

   0x08048413 <+47>:    fldcw  -0x16(%ebp)

   0x08048416 <+50>:    mov    -0x14(%ebp),%eax

   0x08048419 <+53>:    leave  

   0x0804841a <+54>:    ret    

End of assembler dump.

Dump of assembler code for function bar:

   0x0804841b <+0>:     push   %ebp

   0x0804841c <+1>:     mov    %esp,%ebp

   0x0804841e <+3>:     sub    $0x18,%esp

   0x08048421 <+6>:     mov    0xc(%ebp),%eax

   0x08048424 <+9>:     add    $0x5,%eax

   0x08048427 <+12>:    imul   0x8(%ebp),%eax

   0x0804842b <+16>:    mov    %eax,-0x4(%ebp)

   0x0804842e <+19>:    mov    -0x4(%ebp),%eax

   0x08048431 <+22>:    mov    %eax,(%esp)

   0x08048434 <+25>:    call   0x80483e4 <foo>

   0x08048439 <+30>:    leave  

   0x0804843a <+31>:    ret    

End of assembler dump.

谢谢了

...全文