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--- Libc/Libc-583/ppc/string/strncpy.s
+++ Libc/Libc-320/ppc/string/strncpy.s
@@ -2,6 +2,8 @@
* Copyright (c) 2002 Apple Computer, Inc. All rights reserved.
*
* @APPLE_LICENSE_HEADER_START@
+ *
+ * Copyright (c) 1999-2003 Apple Computer, Inc. All Rights Reserved.
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
@@ -24,22 +26,11 @@
#include <mach/ppc/asm.h>
#undef ASSEMBLER
-#define __APPLE_API_PRIVATE
-#include <machine/cpu_capabilities.h>
-#undef __APPLE_API_PRIVATE
-
-/* We use mode-independent "g" opcodes such as "srgi". These expand
- * into word operations when targeting __ppc__, and into doubleword
- * operations when targeting __ppc64__.
- */
-#include <architecture/ppc/mode_independent_asm.h>
-
-
// *****************
// * S T R N C P Y *
// *****************
//
-// char* strncpy(const char *dst, const char *src, size_t len);
+// char* strncpy(const char *dst, const char *src, size_t len));
//
// We optimize the move by doing it word parallel. This introduces
// a complication: if we blindly did word load/stores until finding
@@ -55,28 +46,23 @@
// The test maps any non-zero byte to zero, and any zero byte to 0x80,
// with one exception: 0x01 bytes preceeding the first zero are also
// mapped to 0x80.
-//
-// This algorithm is doubleword parallel in 64-bit mode.
.text
.globl EXT(strncpy)
.align 5
-LEXT(strncpy) // char* strncpy(const char *dst, const char *src, size_t len));
- andi. r0,r4,GPR_BYTES-1 // is source aligned?
-#if defined(__ppc__)
- lis r6,hi16(0xFEFEFEFF) // start to generate 32-bit magic constants
+LEXT(strncpy)
+ andi. r0,r4,3 // is source aligned?
+ dcbt 0,r4 // touch in source
+ lis r6,hi16(0xFEFEFEFF) // start to load magic constants
lis r7,hi16(0x80808080)
+ dcbtst 0,r3 // touch in dst
ori r6,r6,lo16(0xFEFEFEFF)
ori r7,r7,lo16(0x80808080)
-#else
- ld r6,_COMM_PAGE_MAGIC_FE(0) // get 0xFEFEFEFE FEFEFEFF from commpage
- ld r7,_COMM_PAGE_MAGIC_80(0) // get 0x80808080 80808080 from commpage
-#endif
mr r9,r3 // use r9 for dest ptr (must return r3 intact)
add r2,r3,r5 // remember where end of buffer is
beq Laligned // source is aligned
- subfic r0,r0,GPR_BYTES // r0 <- #bytes to align source
+ subfic r0,r0,4 // r0 <- #bytes to word align source
// Copy min(r0,r5) bytes, until 0-byte.
// r0 = #bytes we propose to copy (NOTE: must be >0)
@@ -88,83 +74,148 @@
// r9 = dest ptr (unaligned)
Lbyteloop:
- cmpgi r5,0 // buffer empty? (note: length is unsigned)
+ cmpwi r5,0 // buffer empty? (note: unsigned)
beqlr-- // buffer full but 0 not found
lbz r8,0(r4) // r8 <- next source byte
subic. r0,r0,1 // decrement count of bytes to move
addi r4,r4,1
subi r5,r5,1 // decrement buffer length remaining
+ stb r8,0(r9) // pack into dest
cmpwi cr1,r8,0 // 0-byte?
- stb r8,0(r9) // pack into dest
addi r9,r9,1
beq cr1,L0found // byte was 0
bne Lbyteloop // r0!=0, source not yet aligned
-// Source is aligned. Loop over words or doublewords until end of buffer. Note that
-// we have aligned the source, rather than the dest, in order to avoid spurious
+// Source is word aligned. Loop over words until end of buffer. Note that we
+// have aligned the source, rather than the dest, in order to avoid spurious
// page faults.
// r2 = ptr to 1st byte not in buffer
-// r4 = source ptr (aligned)
+// r4 = source ptr (word aligned)
// r5 = length remaining in buffer
// r6 = 0xFEFEFEFF
// r7 = 0x80808080
// r9 = dest ptr (unaligned)
Laligned:
- srgi. r8,r5,LOG2_GPR_BYTES// get #words or doublewords in buffer
- addi r0,r5,1 // if none, compare rest of buffer
+ srwi. r8,r5,2 // get #words in buffer
+ addi r0,r5,1 // if no words, compare rest of buffer
beq-- Lbyteloop // r8==0, no words
mtctr r8 // set up word loop count
- rlwinm r5,r5,0,GPR_BYTES-1 // mask buffer length down to leftover bytes
- b Lwordloop
-
-// Move a word or a doubleword at a time, until one of two conditions:
+ rlwinm r5,r5,0,0x3 // mask buffer length down to leftover bytes
+ b LwordloopEnter
+
+// Move a word at a time, until one of two conditions:
// - a zero byte is found
// - end of buffer
// At this point, registers are as follows:
// r2 = ptr to 1st byte not in buffer
-// r4 = source ptr (aligned)
-// r5 = leftover bytes in buffer (0..GPR_BYTES-1)
+// r4 = source ptr (word aligned)
+// r5 = leftover bytes in buffer (0..3)
// r6 = 0xFEFEFEFF
// r7 = 0x80808080
// r9 = dest ptr (unaligned)
-// ctr = whole words or doublewords left in buffer
+// ctr = whole words left in buffer
.align 5 // align inner loop, which is 8 words long
Lwordloop:
- lg r8,0(r4) // r8 <- next 4 or 8 source bytes
- addi r9,r9,GPR_BYTES // bump dest addr while we wait for data
- addi r4,r4,GPR_BYTES
+ stw r8,0(r9) // pack word into destination
+ addi r9,r9,4
+LwordloopEnter:
+ lwz r8,0(r4) // r8 <- next 4 source bytes
+ addi r4,r4,4
add r10,r8,r6 // r10 <- word + 0xFEFEFEFF
andc r12,r7,r8 // r12 <- ~word & 0x80808080
- stg r8,-GPR_BYTES(r9) // pack word or doubleword into destination
and. r11,r10,r12 // r11 <- nonzero iff word has a 0-byte
bdnzt eq,Lwordloop // loop if ctr!=0 and cr0_eq
+ stw r8,0(r9) // pack in last word
+ addi r9,r9,4
addi r0,r5,1 // if no 0-byte found...
beq-- Lbyteloop // ...fill rest of buffer a byte at a time
// Found a 0-byte, point to following byte with r9.
- slgi r0,r8,7 // move 0x01 false hit bits to 0x80 position
+ slwi r0,r8,7 // move 0x01 false hit bits to 0x80 position
andc r11,r11,r0 // mask out false hits
- cntlzg r0,r11 // find the 0-byte (r0 = 0,8,16, or 24)
- srwi r0,r0,3 // now r0 = 0, 1, 2, or 3 (0..7 if 64-bit)
- subfic r0,r0,GPR_BYTES-1 // now r0 = 3, 2, 1, or 0
+ cntlzw r0,r11 // find the 0-byte (r0 = 0,8,16, or 24)
+ srwi r0,r0,3 // now r0 = 0, 1, 2, or 3
+ subfic r0,r0,3 // now r0 = 3, 2, 1, or 0
sub r9,r9,r0 // now r9 points one past the 0-byte
-// Zero rest of buffer, if any. We use the commpage bzero() routine.
+// Zero rest of buffer, if any. We don't simply branch to bzero or memset, because
+// r3 is set up incorrectly, and there is a fair amt of overhead involved in using them.
+// Instead we use a simpler routine, which will nonetheless be faster unless the number
+// of bytes to 0 is large and we're on a 64-bit machine.
// r2 = ptr to 1st byte not in buffer
// r9 = ptr to 1st byte to zero
-//
-// NB: commpage bzero() preserves r10-r12 by contract.
L0found:
- mflr r12 // save return
- mr r11,r3 // save original dest ptr
- sub r4,r2,r9 // #bytes to zero (ie, rest of buffer)
- mr r3,r9 // point to 1st byte to zero
- bla _COMM_PAGE_BZERO
- mtlr r12 // restore our return
- mr r3,r11 // restore ptr to original dest
+ sub r5,r2,r9 // r5 <- #bytes to zero (ie, rest of buffer)
+ cmplwi r5,32 // how many?
+ neg r8,r9 // start to compute #bytes to align ptr
+ li r0,0 // get a 0
+ blt Ltail // skip if <32 bytes
+ andi. r10,r8,31 // get #bytes to 32-byte align
+ sub r5,r5,r10 // adjust buffer length
+ srwi r11,r5,5 // get #32-byte chunks
+ cmpwi cr1,r11,0 // any chunks?
+ mtctr r11 // set up dcbz loop count
+ beq 1f // skip if already 32-byte aligned
+
+// 32-byte align. We just store 32 0s, rather than test and use conditional
+// branches.
+
+ stw r0,0(r9) // zero next 32 bytes
+ stw r0,4(r9)
+ stw r0,8(r9)
+ stw r0,12(r9)
+ stw r0,16(r9)
+ stw r0,20(r9)
+ stw r0,24(r9)
+ stw r0,28(r9)
+ add r9,r9,r10 // now r9 is 32-byte aligned
+ beq cr1,Ltail // skip if no 32-byte chunks
+ b 1f
+
+// Loop doing 32-byte version of DCBZ instruction.
+
+ .align 4 // align the inner loop
+1:
+ dcbz 0,r9 // zero another 32 bytes
+ addi r9,r9,32
+ bdnz 1b
+
+// Store trailing bytes.
+// r0 = 0
+// r5 = #bytes to store (<32)
+// r9 = address
+
+Ltail:
+ mtcrf 0x02,r5 // remaining byte count to cr6 and cr7
+ mtcrf 0x01,r5
+ bf 27,2f // 16-byte chunk?
+ stw r0,0(r9)
+ stw r0,4(r9)
+ stw r0,8(r9)
+ stw r0,12(r9)
+ addi r9,r9,16
+2:
+ bf 28,4f // 8-byte chunk?
+ stw r0,0(r9)
+ stw r0,4(r9)
+ addi r9,r9,8
+4:
+ bf 29,5f // word?
+ stw r0,0(r9)
+ addi r9,r9,4
+5:
+ bf 30,6f // halfword?
+ sth r0,0(r9)
+ addi r9,r9,2
+6:
+ bflr 31 // byte?
+ stb r0,0(r9)
blr
+
+
+