| /*#************************************************************************#*/ |
| /*#-------------------------------------------------------------------------*/ |
| /*# */ |
| /*# 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() */ |
