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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libgcc/] [config/] [rl78/] [lshrsi3.S] - Blame information for rev 747

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1 734 jeremybenn
;   Copyright (C) 2011 Free Software Foundation, Inc.
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;   Contributed by Red Hat.
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;
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; This file is free software; you can redistribute it and/or modify it
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; under the terms of the GNU General Public License as published by the
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; Free Software Foundation; either version 3, or (at your option) any
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; later version.
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;
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; This file is distributed in the hope that it will be useful, but
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; WITHOUT ANY WARRANTY; without even the implied warranty of
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; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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; General Public License for more details.
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;
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; Under Section 7 of GPL version 3, you are granted additional
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; permissions described in the GCC Runtime Library Exception, version
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; 3.1, as published by the Free Software Foundation.
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;
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; You should have received a copy of the GNU General Public License and
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; a copy of the GCC Runtime Library Exception along with this program;
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; see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
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; .
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r8      =       0xffef0
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r16     =       0xffee8
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r9      =       0xffef1
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r17     =       0xffee9
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r10     =       0xffef2
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r18     =       0xffeea
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r11     =       0xffef3
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r19     =       0xffeeb
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r12     =       0xffef4
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r20     =       0xffeec
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r13     =       0xffef5
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r21     =       0xffeed
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r14     =       0xffef6
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r22     =       0xffeee
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r15     =       0xffef7
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r23     =       0xffeef
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        .text
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        .global ___lshrsi3
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        .type   ___lshrsi3, @function
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___lshrsi3:
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        ;; input:
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        ;;
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        ;; [zero]
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        ;; [count]   <= $sp+8
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        ;; [in MSB]
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        ;; [in]
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        ;; [in]
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        ;; [in LSB]  <- $sp+4
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        ;; output:
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        ;;
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        ;; [r8..r11] result
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        ;; registers:
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        ;;
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        ;; AX - temp for shift/rotate
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        ;; B  - count
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        mov     a, [sp+8]       ; A now contains the count
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        cmp     a, #0x20
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        bc      $.Lcount_is_normal
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        ;; count is out of bounds, just return zero.
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        movw    r8, #0
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        movw    r10, #0
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        ret
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.Lcount_is_normal:
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        cmp0    a
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        bnz     $.Lcount_is_nonzero
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        ;; count is zero, just copy IN to OUT
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        movw    ax, [sp+4]
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        movw    r8, ax
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        movw    ax, [sp+6]
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        movw    r10, ax
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        ret
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.Lcount_is_nonzero:
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        mov     b, a            ; B now contains the count also
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        bf      a.4, $.Lcount_lt_16
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        ;; count >= 16, shift 16 at a time.
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        movw    r10, #0
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        movw    ax, [sp+6]
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        movw    r8, ax
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        mov     a, b
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        and     a, #0x0f
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        sknz
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        ret
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        mov     b, a            ; B now contains the remaining count
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        inc     b
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        br      $.Lloop_top
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.Lcount_lt_16:
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        ;; count is nonzero.  Do one
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        movw    ax, [sp+6]
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        shrw    ax,1
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        movw    r10, ax
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        mov     a, [sp+5]
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        rorc    a,1
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        mov     r9, a
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        mov     a, [sp+4]
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        rorc    a,1
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        mov     r8, a
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        ;; we did one shift above; do as many more as we need now.
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.Lloop_top:
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        dec     b
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        sknz
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        ret
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        movw    ax, r10
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        shrw    ax,1
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        movw    r10, ax
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        mov     a, r9
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        rorc    a,1
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        mov     r9, a
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        mov     a, r8
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        rorc    a,1
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        mov     r8, a
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        br      $.Lloop_top
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        .size   ___lshrsi3, .-___lshrsi3

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