root/arch/x86/math-emu/shr_Xsig.S

        .file   "shr_Xsig.S"
/*---------------------------------------------------------------------------+
 |  shr_Xsig.S                                                               |
 |                                                                           |
 | 12 byte right shift function                                              |
 |                                                                           |
 | Copyright (C) 1992,1994,1995                                              |
 |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |
 |                       Australia.  E-mail billm@jacobi.maths.monash.edu.au |
 |                                                                           |
 | Call from C as:                                                           |
 |   void shr_Xsig(Xsig *arg, unsigned nr)                                   |
 |                                                                           |
 |   Extended shift right function.                                          |
 |   Fastest for small shifts.                                               |
 |   Shifts the 12 byte quantity pointed to by the first arg (arg)           |
 |   right by the number of bits specified by the second arg (nr).           |
 |                                                                           |
 +---------------------------------------------------------------------------*/

#include "fpu_emu.h"

.text
ENTRY(shr_Xsig)
        push    %ebp
        movl    %esp,%ebp
        pushl   %esi
        movl    PARAM2,%ecx
        movl    PARAM1,%esi
        cmpl    $32,%ecx        /* shrd only works for 0..31 bits */
        jnc     L_more_than_31

/* less than 32 bits */
        pushl   %ebx
        movl    (%esi),%eax     /* lsl */
        movl    4(%esi),%ebx    /* midl */
        movl    8(%esi),%edx    /* msl */
        shrd    %cl,%ebx,%eax
        shrd    %cl,%edx,%ebx
        shr     %cl,%edx
        movl    %eax,(%esi)
        movl    %ebx,4(%esi)
        movl    %edx,8(%esi)
        popl    %ebx
        popl    %esi
        leave
        ret

L_more_than_31:
        cmpl    $64,%ecx
        jnc     L_more_than_63

        subb    $32,%cl
        movl    4(%esi),%eax    /* midl */
        movl    8(%esi),%edx    /* msl */
        shrd    %cl,%edx,%eax
        shr     %cl,%edx
        movl    %eax,(%esi)
        movl    %edx,4(%esi)
        movl    $0,8(%esi)
        popl    %esi
        leave
        ret

L_more_than_63:
        cmpl    $96,%ecx
        jnc     L_more_than_95

        subb    $64,%cl
        movl    8(%esi),%eax    /* msl */
        shr     %cl,%eax
        xorl    %edx,%edx
        movl    %eax,(%esi)
        movl    %edx,4(%esi)
        movl    %edx,8(%esi)
        popl    %esi
        leave
        ret

L_more_than_95:
        xorl    %eax,%eax
        movl    %eax,(%esi)
        movl    %eax,4(%esi)
        movl    %eax,8(%esi)
        popl    %esi
        leave
        ret