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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/cris/arch-v10/lib/string.c
downloadlinux-stericsson-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'arch/cris/arch-v10/lib/string.c')
-rw-r--r--arch/cris/arch-v10/lib/string.c225
1 files changed, 225 insertions, 0 deletions
diff --git a/arch/cris/arch-v10/lib/string.c b/arch/cris/arch-v10/lib/string.c
new file mode 100644
index 000000000000..8ffde4901b57
--- /dev/null
+++ b/arch/cris/arch-v10/lib/string.c
@@ -0,0 +1,225 @@
+/*#************************************************************************#*/
+/*#-------------------------------------------------------------------------*/
+/*# */
+/*# FUNCTION NAME: memcpy() */
+/*# */
+/*# PARAMETERS: void* dst; Destination address. */
+/*# void* src; Source address. */
+/*# int len; Number of bytes to copy. */
+/*# */
+/*# RETURNS: dst. */
+/*# */
+/*# DESCRIPTION: Copies len bytes of memory from src to dst. No guarantees */
+/*# about copying of overlapping memory areas. This routine is */
+/*# very sensitive to compiler changes in register allocation. */
+/*# Should really be rewritten to avoid this problem. */
+/*# */
+/*#-------------------------------------------------------------------------*/
+/*# */
+/*# HISTORY */
+/*# */
+/*# DATE NAME CHANGES */
+/*# ---- ---- ------- */
+/*# 941007 Kenny R Creation */
+/*# 941011 Kenny R Lots of optimizations and inlining. */
+/*# 941129 Ulf A Adapted for use in libc. */
+/*# 950216 HP N==0 forgotten if non-aligned src/dst. */
+/*# Added some optimizations. */
+/*# 001025 HP Make src and dst char *. Align dst to */
+/*# dword, not just word-if-both-src-and-dst- */
+/*# are-misaligned. */
+/*# */
+/*#-------------------------------------------------------------------------*/
+
+#include <linux/types.h>
+
+void *memcpy(void *pdst,
+ const void *psrc,
+ size_t pn)
+{
+ /* Ok. Now we want the parameters put in special registers.
+ Make sure the compiler is able to make something useful of this.
+ As it is now: r10 -> r13; r11 -> r11 (nop); r12 -> r12 (nop).
+
+ If gcc was allright, it really would need no temporaries, and no
+ stack space to save stuff on. */
+
+ register void *return_dst __asm__ ("r10") = pdst;
+ register char *dst __asm__ ("r13") = pdst;
+ register const char *src __asm__ ("r11") = psrc;
+ register int n __asm__ ("r12") = pn;
+
+
+ /* When src is aligned but not dst, this makes a few extra needless
+ cycles. I believe it would take as many to check that the
+ re-alignment was unnecessary. */
+ if (((unsigned long) dst & 3) != 0
+ /* Don't align if we wouldn't copy more than a few bytes; so we
+ don't have to check further for overflows. */
+ && n >= 3)
+ {
+ if ((unsigned long) dst & 1)
+ {
+ n--;
+ *(char*)dst = *(char*)src;
+ src++;
+ dst++;
+ }
+
+ if ((unsigned long) dst & 2)
+ {
+ n -= 2;
+ *(short*)dst = *(short*)src;
+ src += 2;
+ dst += 2;
+ }
+ }
+
+ /* Decide which copying method to use. */
+ if (n >= 44*2) /* Break even between movem and
+ move16 is at 38.7*2, but modulo 44. */
+ {
+ /* 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.
+
+ If you want to check that the allocation was right; then
+ check the equalities in the first comment. It should say
+ "r13=r13, r11=r11, r12=r12" */
+ __asm__ volatile ("
+ ;; Check that the following is true (same register names on
+ ;; both sides of equal sign, as in r8=r8):
+ ;; %0=r13, %1=r11, %2=r12
+ ;;
+ ;; Save the registers we'll use in the movem process
+ ;; on the stack.
+ subq 11*4,$sp
+ movem $r10,[$sp]
+
+ ;; Now we've got this:
+ ;; r11 - src
+ ;; r13 - dst
+ ;; r12 - n
+
+ ;; Update n for the first loop
+ subq 44,$r12
+0:
+ movem [$r11+],$r10
+ subq 44,$r12
+ bge 0b
+ movem $r10,[$r13+]
+
+ addq 44,$r12 ;; compensate for last loop underflowing n
+
+ ;; Restore registers from stack
+ movem [$sp+],$r10"
+
+ /* Outputs */ : "=r" (dst), "=r" (src), "=r" (n)
+ /* Inputs */ : "0" (dst), "1" (src), "2" (n));
+
+ }
+
+ /* 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)++ = *((long*)src)++;
+ *((long*)dst)++ = *((long*)src)++;
+ *((long*)dst)++ = *((long*)src)++;
+ *((long*)dst)++ = *((long*)src)++;
+ 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*)src;
+ break;
+ case 2:
+ *(short*)dst = *(short*)src;
+ break;
+ case 3:
+ *((short*)dst)++ = *((short*)src)++;
+ *(char*)dst = *(char*)src;
+ break;
+ case 4:
+ *((long*)dst)++ = *((long*)src)++;
+ break;
+ case 5:
+ *((long*)dst)++ = *((long*)src)++;
+ *(char*)dst = *(char*)src;
+ break;
+ case 6:
+ *((long*)dst)++ = *((long*)src)++;
+ *(short*)dst = *(short*)src;
+ break;
+ case 7:
+ *((long*)dst)++ = *((long*)src)++;
+ *((short*)dst)++ = *((short*)src)++;
+ *(char*)dst = *(char*)src;
+ break;
+ case 8:
+ *((long*)dst)++ = *((long*)src)++;
+ *((long*)dst)++ = *((long*)src)++;
+ break;
+ case 9:
+ *((long*)dst)++ = *((long*)src)++;
+ *((long*)dst)++ = *((long*)src)++;
+ *(char*)dst = *(char*)src;
+ break;
+ case 10:
+ *((long*)dst)++ = *((long*)src)++;
+ *((long*)dst)++ = *((long*)src)++;
+ *(short*)dst = *(short*)src;
+ break;
+ case 11:
+ *((long*)dst)++ = *((long*)src)++;
+ *((long*)dst)++ = *((long*)src)++;
+ *((short*)dst)++ = *((short*)src)++;
+ *(char*)dst = *(char*)src;
+ break;
+ case 12:
+ *((long*)dst)++ = *((long*)src)++;
+ *((long*)dst)++ = *((long*)src)++;
+ *((long*)dst)++ = *((long*)src)++;
+ break;
+ case 13:
+ *((long*)dst)++ = *((long*)src)++;
+ *((long*)dst)++ = *((long*)src)++;
+ *((long*)dst)++ = *((long*)src)++;
+ *(char*)dst = *(char*)src;
+ break;
+ case 14:
+ *((long*)dst)++ = *((long*)src)++;
+ *((long*)dst)++ = *((long*)src)++;
+ *((long*)dst)++ = *((long*)src)++;
+ *(short*)dst = *(short*)src;
+ break;
+ case 15:
+ *((long*)dst)++ = *((long*)src)++;
+ *((long*)dst)++ = *((long*)src)++;
+ *((long*)dst)++ = *((long*)src)++;
+ *((short*)dst)++ = *((short*)src)++;
+ *(char*)dst = *(char*)src;
+ break;
+ }
+
+ return return_dst; /* destination pointer. */
+} /* memcpy() */