summaryrefslogtreecommitdiff
path: root/libc/string/cris/memset.c
diff options
context:
space:
mode:
Diffstat (limited to 'libc/string/cris/memset.c')
-rw-r--r--libc/string/cris/memset.c271
1 files changed, 271 insertions, 0 deletions
diff --git a/libc/string/cris/memset.c b/libc/string/cris/memset.c
new file mode 100644
index 000000000..7e71bc50f
--- /dev/null
+++ b/libc/string/cris/memset.c
@@ -0,0 +1,271 @@
+/* Copyright (C) 2001, 2003 Free Software Foundation, Inc.
+ Copyright (C) 1999, 2000 Axis Communications AB.
+
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Library General Public License as
+ published by the Free Software Foundation; either version 2 of the
+ License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Library General Public License for more details.
+
+ You should have received a copy of the GNU Library General Public
+ License along with the GNU C Library; see the file COPYING.LIB. If not,
+ write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA. */
+
+/*#************************************************************************#*/
+/*#-------------------------------------------------------------------------*/
+/*# */
+/*# FUNCTION NAME: memset() */
+/*# */
+/*# PARAMETERS: void* dst; Destination address. */
+/*# int c; Value of byte to write. */
+/*# int len; Number of bytes to write. */
+/*# */
+/*# RETURNS: dst. */
+/*# */
+/*# DESCRIPTION: Sets the memory dst of length len bytes to c, as standard. */
+/*# Framework taken from memcpy. This routine is */
+/*# very sensitive to compiler changes in register allocation. */
+/*# Should really be rewritten to avoid this problem. */
+/*# */
+/*#-------------------------------------------------------------------------*/
+/*# */
+/*# HISTORY */
+/*# */
+/*# DATE NAME CHANGES */
+/*# ---- ---- ------- */
+/*# 990713 HP Tired of watching this function (or */
+/*# really, the nonoptimized generic */
+/*# implementation) take up 90% of simulator */
+/*# output. Measurements needed. */
+/*# */
+/*#-------------------------------------------------------------------------*/
+
+/* No, there's no macro saying 12*4, since it is "hard" to get it into
+ the asm in a good way. Thus better to expose the problem everywhere.
+ */
+
+/* Assuming 1 cycle per dword written or read (ok, not really true), and
+ one per instruction, then 43+3*(n/48-1) <= 24+24*(n/48-1)
+ so n >= 45.7; n >= 0.9; we win on the first full 48-byte block to set. */
+
+#define ZERO_BLOCK_SIZE (1*12*4)
+
+void *memset(void *, int, unsigned long);
+
+libc_hidden_proto(memset)
+void *memset(void *pdst,
+ int c,
+ unsigned long plen)
+{
+ /* Ok. Now we want the parameters put in special registers.
+ Make sure the compiler is able to make something useful of this. */
+
+ register char *return_dst __asm__ ("r10") = pdst;
+ register long n __asm__ ("r12") = plen;
+ register int lc __asm__ ("r11") = c;
+
+ /* Most apps use memset sanely. Only those memsetting about 3..4
+ bytes or less get penalized compared to the generic implementation
+ - and that's not really sane use. */
+
+ /* Ugh. This is fragile at best. Check with newer GCC releases, if
+ they compile cascaded "x |= x << 8" sanely! */
+ __asm__("movu.b %0,$r13 \n\
+ lslq 8,$r13 \n\
+ move.b %0,$r13 \n\
+ move.d $r13,%0 \n\
+ lslq 16,$r13 \n\
+ or.d $r13,%0"
+ : "=r" (lc) : "0" (lc) : "r13");
+
+ {
+ register char *dst __asm__ ("r13") = pdst;
+
+ if (((unsigned long) pdst & 3) != 0
+ /* Oops! n=0 must be a legal call, regardless of alignment. */
+ && n >= 3)
+ {
+ if ((unsigned long)dst & 1)
+ {
+ *dst = (char) lc;
+ n--;
+ dst++;
+ }
+
+ if ((unsigned long)dst & 2)
+ {
+ *(short *)dst = lc;
+ n -= 2;
+ dst += 2;
+ }
+ }
+
+ /* Now the fun part. For the threshold value of this, check the equation
+ above. */
+ /* Decide which copying method to use. */
+ if (n >= ZERO_BLOCK_SIZE)
+ {
+ /* For large copies we use 'movem' */
+
+ /* It is not optimal to tell the compiler about clobbering any
+ registers; that will move the saving/restoring of those registers
+ to the function prologue/epilogue, and make non-movem sizes
+ suboptimal.
+
+ This method is not foolproof; it assumes that the "asm reg"
+ declarations at the beginning of the function really are used
+ here (beware: they may be moved to temporary registers).
+ This way, we do not have to save/move the registers around into
+ temporaries; we can safely use them straight away. */
+ __asm__ volatile (" \n\
+ .syntax no_register_prefix \n\
+ \n\
+ ;; Check that the register asm declaration got right. \n\
+ ;; The GCC manual explicitly says there's no warranty for that (too). \n\
+ .ifnc %0-%1-%4,$r13-$r12-$r11 \n\
+ .err \n\
+ .endif \n\
+ \n\
+ ;; Save the registers we'll clobber in the movem process \n\
+ ;; on the stack. Don't mention them to gcc, it will only be \n\
+ ;; upset. \n\
+ subq 11*4,sp \n\
+ movem r10,[sp] \n\
+ \n\
+ move.d r11,r0 \n\
+ move.d r11,r1 \n\
+ move.d r11,r2 \n\
+ move.d r11,r3 \n\
+ move.d r11,r4 \n\
+ move.d r11,r5 \n\
+ move.d r11,r6 \n\
+ move.d r11,r7 \n\
+ move.d r11,r8 \n\
+ move.d r11,r9 \n\
+ move.d r11,r10 \n\
+ \n\
+ ;; Now we've got this: \n\
+ ;; r13 - dst \n\
+ ;; r12 - n \n\
+ \n\
+ ;; Update n for the first loop \n\
+ subq 12*4,r12 \n\
+0: \n\
+ subq 12*4,r12 \n\
+ bge 0b \n\
+ movem r11,[r13+] \n\
+ \n\
+ addq 12*4,r12 ;; compensate for last loop underflowing n \n\
+ \n\
+ ;; Restore registers from stack \n\
+ movem [sp+],r10"
+
+ /* Outputs */ : "=r" (dst), "=r" (n)
+ /* Inputs */ : "0" (dst), "1" (n), "r" (lc));
+
+ }
+
+ /* Either we directly starts copying, using dword copying
+ in a loop, or we copy as much as possible with 'movem'
+ and then the last block (<44 bytes) is copied here.
+ This will work since 'movem' will have updated src,dst,n. */
+
+ while ( n >= 16 )
+ {
+ *((long*)dst)++ = lc;
+ *((long*)dst)++ = lc;
+ *((long*)dst)++ = lc;
+ *((long*)dst)++ = lc;
+ n -= 16;
+ }
+
+ /* A switch() is definitely the fastest although it takes a LOT of code.
+ * Particularly if you inline code this.
+ */
+ switch (n)
+ {
+ case 0:
+ break;
+ case 1:
+ *(char*)dst = (char) lc;
+ break;
+ case 2:
+ *(short*)dst = (short) lc;
+ break;
+ case 3:
+ *((short*)dst)++ = (short) lc;
+ *(char*)dst = (char) lc;
+ break;
+ case 4:
+ *((long*)dst)++ = lc;
+ break;
+ case 5:
+ *((long*)dst)++ = lc;
+ *(char*)dst = (char) lc;
+ break;
+ case 6:
+ *((long*)dst)++ = lc;
+ *(short*)dst = (short) lc;
+ break;
+ case 7:
+ *((long*)dst)++ = lc;
+ *((short*)dst)++ = (short) lc;
+ *(char*)dst = (char) lc;
+ break;
+ case 8:
+ *((long*)dst)++ = lc;
+ *((long*)dst)++ = lc;
+ break;
+ case 9:
+ *((long*)dst)++ = lc;
+ *((long*)dst)++ = lc;
+ *(char*)dst = (char) lc;
+ break;
+ case 10:
+ *((long*)dst)++ = lc;
+ *((long*)dst)++ = lc;
+ *(short*)dst = (short) lc;
+ break;
+ case 11:
+ *((long*)dst)++ = lc;
+ *((long*)dst)++ = lc;
+ *((short*)dst)++ = (short) lc;
+ *(char*)dst = (char) lc;
+ break;
+ case 12:
+ *((long*)dst)++ = lc;
+ *((long*)dst)++ = lc;
+ *((long*)dst)++ = lc;
+ break;
+ case 13:
+ *((long*)dst)++ = lc;
+ *((long*)dst)++ = lc;
+ *((long*)dst)++ = lc;
+ *(char*)dst = (char) lc;
+ break;
+ case 14:
+ *((long*)dst)++ = lc;
+ *((long*)dst)++ = lc;
+ *((long*)dst)++ = lc;
+ *(short*)dst = (short) lc;
+ break;
+ case 15:
+ *((long*)dst)++ = lc;
+ *((long*)dst)++ = lc;
+ *((long*)dst)++ = lc;
+ *((short*)dst)++ = (short) lc;
+ *(char*)dst = (char) lc;
+ break;
+ }
+ }
+
+ return return_dst; /* destination pointer. */
+} /* memset() */
+libc_hidden_def(memset)
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-03 18:53:29 +0000