253 lines
8.2 KiB
C
253 lines
8.2 KiB
C
|
/*#************************************************************************#*/
|
||
|
|
/*#-------------------------------------------------------------------------*/
|
||
|
|
/*# */
|
||
|
|
/*# 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. */
|
||
|
|
/*# */
|
||
|
|
/*#-------------------------------------------------------------------------*/
|
||
|
|
|
||
|
|
#include <linux/types.h>
|
||
|
|
|
||
|
|
/* 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 *pdst,
|
||
|
|
int c,
|
||
|
|
size_t 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 int 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,$r13\n\t"
|
||
|
|
"lslq 8,$r13\n\t"
|
||
|
|
"move.b %0,$r13\n\t"
|
||
|
|
"move.d $r13,%0\n\t"
|
||
|
|
"lslq 16,$r13\n\t"
|
||
|
|
"or.d $r13,%0"
|
||
|
|
: "=r" (lc) : "0" (lc) : "r13");
|
||
|
|
|
||
|
|
{
|
||
|
|
register char *dst __asm__ ("r13") = pdst;
|
||
|
|
|
||
|
|
/* This is NONPORTABLE, but since this whole routine is */
|
||
|
|
/* grossly nonportable that doesn't matter. */
|
||
|
|
|
||
|
|
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.
|
||
|
|
|
||
|
|
If you want to check that the allocation was right; then
|
||
|
|
check the equalities in the first comment. It should say
|
||
|
|
"r13=r13, r12=r12, r11=r11" */
|
||
|
|
__asm__ volatile ("
|
||
|
|
;; Check that the following is true (same register names on
|
||
|
|
;; both sides of equal sign, as in r8=r8):
|
||
|
|
;; %0=r13, %1=r12, %4=r11
|
||
|
|
;;
|
||
|
|
;; Save the registers we'll clobber in the movem process
|
||
|
|
;; on the stack. Don't mention them to gcc, it will only be
|
||
|
|
;; upset.
|
||
|
|
subq 11*4,$sp
|
||
|
|
movem $r10,[$sp]
|
||
|
|
|
||
|
|
move.d $r11,$r0
|
||
|
|
move.d $r11,$r1
|
||
|
|
move.d $r11,$r2
|
||
|
|
move.d $r11,$r3
|
||
|
|
move.d $r11,$r4
|
||
|
|
move.d $r11,$r5
|
||
|
|
move.d $r11,$r6
|
||
|
|
move.d $r11,$r7
|
||
|
|
move.d $r11,$r8
|
||
|
|
move.d $r11,$r9
|
||
|
|
move.d $r11,$r10
|
||
|
|
|
||
|
|
;; Now we've got this:
|
||
|
|
;; r13 - dst
|
||
|
|
;; r12 - n
|
||
|
|
|
||
|
|
;; Update n for the first loop
|
||
|
|
subq 12*4,$r12
|
||
|
|
0:
|
||
|
|
subq 12*4,$r12
|
||
|
|
bge 0b
|
||
|
|
movem $r11,[$r13+]
|
||
|
|
|
||
|
|
addq 12*4,$r12 ;; compensate for last loop underflowing n
|
||
|
|
|
||
|
|
;; Restore registers from stack
|
||
|
|
movem [$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() */
|