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Annotation of sys/lib/libkern/arch/sh/udivsi3.S, Revision 1.1.1.1

1.1       nbrk        1: /*     $NetBSD: udivsi3.S,v 1.7 2006/05/22 20:56:44 uwe Exp $  */
                      2:
                      3: /*-
                      4:  * Copyright (c) 1990 The Regents of the University of California.
                      5:  * All rights reserved.
                      6:  *
                      7:  * This code is derived from software contributed to Berkeley by
                      8:  * William Jolitz.
                      9:  *
                     10:  * Redistribution and use in source and binary forms, with or without
                     11:  * modification, are permitted provided that the following conditions
                     12:  * are met:
                     13:  * 1. Redistributions of source code must retain the above copyright
                     14:  *    notice, this list of conditions and the following disclaimer.
                     15:  * 2. Redistributions in binary form must reproduce the above copyright
                     16:  *    notice, this list of conditions and the following disclaimer in the
                     17:  *    documentation and/or other materials provided with the distribution.
                     18:  * 3. Neither the name of the University nor the names of its contributors
                     19:  *    may be used to endorse or promote products derived from this software
                     20:  *    without specific prior written permission.
                     21:  *
                     22:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
                     23:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     24:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     25:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
                     26:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     27:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     28:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     29:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     30:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     31:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     32:  * SUCH DAMAGE.
                     33:  *
                     34:  *     from: @(#)udivsi3.s     5.1 (Berkeley) 5/15/90
                     35:  */
                     36:
                     37: #include <machine/asm.h>
                     38:
                     39: /*
                     40:  * IMPORTANT: This function is special.
                     41:  *
                     42:  * This function is an auxiliary function that is referenced by the
                     43:  * code generated by gcc for integer division.  But gcc does NOT treat
                     44:  * a call to this function as an ordinary function call w.r.t. the set
                     45:  * of register this call clobbers.  See the definition of "udivsi3_i1"
                     46:  * in gcc/config/sh/sh.md.
                     47:  *
                     48:  * Any call to this function MUST NOT clobber any registers besides r4
                     49:  * and r0, where the result is returned.  At the time of the call the
                     50:  * r4 contains the first argument, so we are only left with r0, and we
                     51:  * cannot do anything meaningful using only one register.  The
                     52:  * consequences are:
                     53:  *
                     54:  * . this function cannot have _PROF_PROLOGUE
                     55:  * . this function cannot be called via PLT
                     56:  */
                     57:
                     58:
                     59: /* r0 <= r4 / r5 */
                     60: NENTRY(__udivsi3)
                     61:        tst     r5, r5
                     62:        bt      div_by_zero
                     63:
                     64:        mov     #0, r0
                     65:        div0u
                     66: #define DIVSTEP        rotcl r4; div1 r5, r0
                     67:        /* repeat 32 times */
                     68:        DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP;
                     69:        DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP;
                     70:        DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP;
                     71:        DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP; DIVSTEP;
                     72: #undef DIVSTEP
                     73:        rotcl   r4
                     74:
                     75:        rts
                     76:         mov    r4, r0
                     77:
                     78: div_by_zero:
                     79: #ifdef _KERNEL
                     80:        rts
                     81:         mov    #0, r0
                     82: #else
                     83:        mov.l   r14, @-r15
                     84:        sts.l   pr, @-r15
                     85:        mov     r15, r14
                     86:
                     87:        mov.l   L_raise, r1
                     88: #ifdef PIC
                     89: 1:     bsrf    r1
                     90: #else
                     91:        jsr     @r1
                     92: #endif
                     93:         mov    #8, r4          /* delay slot.  8 <- SIGFPE. */
                     94:        mov     #0, r0
                     95:
                     96:        lds.l   @r15+, pr
                     97:        rts
                     98:         mov.l  @r15+, r14
                     99:
                    100:        .align  2
                    101: L_raise:
                    102: #ifdef PIC
                    103:        .long   _C_LABEL(raise)-(1b+4)
                    104: #else
                    105:        .long   _C_LABEL(raise)
                    106: #endif
                    107: #endif