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