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jeremybenn |
/* 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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