77a746cec5
Adrian Bunk reported the following compile error with a SVN head GCC:
...
CC arch/cris/arch-v10/lib/memset.o
/home/bunk/linux/kernel-2.6/git/linux-2.6/arch/cris/arch-v10/lib/memset.c: In function 'memset':
/home/bunk/linux/kernel-2.6/git/linux-2.6/arch/cris/arch-v10/lib/memset.c:164: error: lvalue required as increment operand
/home/bunk/linux/kernel-2.6/git/linux-2.6/arch/cris/arch-v10/lib/memset.c:165: error: lvalue required as increment operand
/home/bunk/linux/kernel-2.6/git/linux-2.6/arch/cris/arch-v10/lib/memset.c:166: error: lvalue required as increment operand
/home/bunk/linux/kernel-2.6/git/linux-2.6/arch/cris/arch-v10/lib/memset.c:167: error: lvalue required as increment operand
/home/bunk/linux/kernel-2.6/git/linux-2.6/arch/cris/arch-v10/lib/memset.c:185: error: lvalue required as increment operand
/home/bunk/linux/kernel-2.6/git/linux-2.6/arch/cris/arch-v10/lib/memset.c:189: error: lvalue required as increment operand
/home/bunk/linux/kernel-2.6/git/linux-2.6/arch/cris/arch-v10/lib/memset.c:192: error: lvalue required as increment operand
... etc ...
This is due to the use of the construct:
*((long*)dst)++ = lc;
Which is no longer legal since casts don't return an lvalue.
The solution is to import the implementation from newlib,
which is continually autotested together with GCC mainline,
and uses the construct:
*(long *) dst = lc; dst += 4;
With this change, the generated code actually shrinks 76 bytes
since gcc notices that it can use autoincrement for the move
instruction in CRIS.
text data bss dec hex filename
304 0 0 304 130 memset.old.o
text data bss dec hex filename
228 0 0 228 e4 memset.o
Since this is an import of a file from newlib, I'm not touching
the formatting or correcting any checkpatch errors.
Note also that even if the two files for the CRIS v10 and CRIS v32
are identical at the moment, it might be possible to tweak the
CRIS v32 version. Thus, I'm not yet folding them into the same file,
at least not until we've done some research on it.
Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Mikael Starvik <mikael.starvik@axis.com>
Cc: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
259 lines
7.3 KiB
C
259 lines
7.3 KiB
C
/* A memset for CRIS.
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Copyright (C) 1999-2005 Axis Communications.
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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1. Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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2. Neither the name of Axis Communications nor the names of its
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contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY AXIS COMMUNICATIONS AND ITS CONTRIBUTORS
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``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL AXIS
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COMMUNICATIONS OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
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INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE. */
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/* FIXME: This file should really only be used for reference, as the
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result is somewhat depending on gcc generating what we expect rather
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than what we describe. An assembly file should be used instead. */
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/* Note the multiple occurrence of the expression "12*4", including the
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asm. It is hard to get it into the asm in a good way. Thus better to
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expose the problem everywhere: no macro. */
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/* Assuming one cycle per dword written or read (ok, not really true; the
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world is not ideal), and one cycle per instruction, then 43+3*(n/48-1)
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<= 24+24*(n/48-1) so n >= 45.7; n >= 0.9; we win on the first full
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48-byte block to set. */
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#define MEMSET_BY_BLOCK_THRESHOLD (1 * 48)
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/* No name ambiguities in this file. */
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__asm__ (".syntax no_register_prefix");
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void *memset(void *pdst, int c, unsigned int plen)
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{
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/* Now we want the parameters in special registers. Make sure the
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compiler does something usable with this. */
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register char *return_dst __asm__ ("r10") = pdst;
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register int n __asm__ ("r12") = plen;
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register int lc __asm__ ("r11") = c;
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/* Most apps use memset sanely. Memsetting about 3..4 bytes or less get
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penalized here compared to the generic implementation. */
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/* This is fragile performancewise at best. Check with newer GCC
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releases, if they compile cascaded "x |= x << 8" to sane code. */
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__asm__("movu.b %0,r13 \n\
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lslq 8,r13 \n\
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move.b %0,r13 \n\
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move.d r13,%0 \n\
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lslq 16,r13 \n\
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or.d r13,%0"
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: "=r" (lc) /* Inputs. */
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: "0" (lc) /* Outputs. */
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: "r13"); /* Trash. */
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{
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register char *dst __asm__ ("r13") = pdst;
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if (((unsigned long) pdst & 3) != 0
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/* Oops! n = 0 must be a valid call, regardless of alignment. */
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&& n >= 3)
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{
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if ((unsigned long) dst & 1)
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{
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*dst = (char) lc;
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n--;
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dst++;
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}
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if ((unsigned long) dst & 2)
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{
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*(short *) dst = lc;
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n -= 2;
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dst += 2;
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}
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}
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/* Decide which setting method to use. */
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if (n >= MEMSET_BY_BLOCK_THRESHOLD)
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{
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/* It is not optimal to tell the compiler about clobbering any
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registers; that will move the saving/restoring of those registers
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to the function prologue/epilogue, and make non-block sizes
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suboptimal. */
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__asm__ volatile
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("\
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;; GCC does promise correct register allocations, but let's \n\
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;; make sure it keeps its promises. \n\
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.ifnc %0-%1-%4,$r13-$r12-$r11 \n\
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.error \"GCC reg alloc bug: %0-%1-%4 != $r13-$r12-$r11\" \n\
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.endif \n\
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\n\
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;; Save the registers we'll clobber in the movem process \n\
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;; on the stack. Don't mention them to gcc, it will only be \n\
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;; upset. \n\
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subq 11*4,sp \n\
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movem r10,[sp] \n\
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\n\
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move.d r11,r0 \n\
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move.d r11,r1 \n\
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move.d r11,r2 \n\
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move.d r11,r3 \n\
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move.d r11,r4 \n\
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move.d r11,r5 \n\
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move.d r11,r6 \n\
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move.d r11,r7 \n\
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move.d r11,r8 \n\
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move.d r11,r9 \n\
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move.d r11,r10 \n\
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\n\
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;; Now we've got this: \n\
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;; r13 - dst \n\
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;; r12 - n \n\
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\n\
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;; Update n for the first loop \n\
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subq 12*4,r12 \n\
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0: \n\
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"
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#ifdef __arch_common_v10_v32
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/* Cater to branch offset difference between v32 and v10. We
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assume the branch below has an 8-bit offset. */
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" setf\n"
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#endif
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" subq 12*4,r12 \n\
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bge 0b \n\
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movem r11,[r13+] \n\
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\n\
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;; Compensate for last loop underflowing n. \n\
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addq 12*4,r12 \n\
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\n\
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;; Restore registers from stack. \n\
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movem [sp+],r10"
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/* Outputs. */
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: "=r" (dst), "=r" (n)
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/* Inputs. */
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: "0" (dst), "1" (n), "r" (lc));
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}
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/* An ad-hoc unroll, used for 4*12-1..16 bytes. */
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while (n >= 16)
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{
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*(long *) dst = lc; dst += 4;
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*(long *) dst = lc; dst += 4;
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*(long *) dst = lc; dst += 4;
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*(long *) dst = lc; dst += 4;
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n -= 16;
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}
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switch (n)
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{
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case 0:
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break;
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case 1:
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*dst = (char) lc;
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break;
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case 2:
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*(short *) dst = (short) lc;
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break;
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case 3:
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*(short *) dst = (short) lc; dst += 2;
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*dst = (char) lc;
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break;
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case 4:
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*(long *) dst = lc;
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break;
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case 5:
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*(long *) dst = lc; dst += 4;
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*dst = (char) lc;
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break;
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case 6:
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*(long *) dst = lc; dst += 4;
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*(short *) dst = (short) lc;
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break;
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case 7:
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*(long *) dst = lc; dst += 4;
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*(short *) dst = (short) lc; dst += 2;
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*dst = (char) lc;
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break;
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case 8:
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*(long *) dst = lc; dst += 4;
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*(long *) dst = lc;
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break;
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case 9:
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*(long *) dst = lc; dst += 4;
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*(long *) dst = lc; dst += 4;
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*dst = (char) lc;
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break;
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case 10:
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*(long *) dst = lc; dst += 4;
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*(long *) dst = lc; dst += 4;
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*(short *) dst = (short) lc;
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break;
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case 11:
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*(long *) dst = lc; dst += 4;
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*(long *) dst = lc; dst += 4;
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*(short *) dst = (short) lc; dst += 2;
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*dst = (char) lc;
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break;
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case 12:
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*(long *) dst = lc; dst += 4;
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*(long *) dst = lc; dst += 4;
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*(long *) dst = lc;
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break;
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case 13:
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*(long *) dst = lc; dst += 4;
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*(long *) dst = lc; dst += 4;
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*(long *) dst = lc; dst += 4;
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*dst = (char) lc;
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break;
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case 14:
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*(long *) dst = lc; dst += 4;
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*(long *) dst = lc; dst += 4;
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*(long *) dst = lc; dst += 4;
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*(short *) dst = (short) lc;
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break;
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case 15:
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*(long *) dst = lc; dst += 4;
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*(long *) dst = lc; dst += 4;
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*(long *) dst = lc; dst += 4;
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*(short *) dst = (short) lc; dst += 2;
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*dst = (char) lc;
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break;
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}
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}
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return return_dst;
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}
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