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--- Libc/Libc-583/ppc/string/strcat.s
+++ Libc/Libc-320/ppc/string/strcat.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
@@ -24,17 +26,6 @@
#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 C A T *
// ***************
@@ -44,7 +35,7 @@
// We optimize the move by doing it word parallel. This introduces
// a complication: if we blindly did word load/stores until finding
// a 0, we might get a spurious page fault by touching bytes past it.
-// To avoid this, we never do a load that crosses a page boundary,
+// To avoid this, we never do a "lwz" that crosses a page boundary,
// and never store a byte we don't have to.
//
// The test for 0s relies on the following inobvious but very efficient
@@ -55,69 +46,75 @@
// 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.
-//
-// In 64-bit mode, this algorithm is doubleword parallel.
.text
.globl EXT(strcat)
.align 5
-LEXT(strcat) // char* strcat(const char *s, const char *append);
- clrrgi r9,r3,LOG2_GPR_BYTES// align pointer by zeroing right LOG2_GPR_BYTES bits
- li r10,-1 // get 0xFFs
- lg r8,0(r9) // get word or doubleword with 1st operand byte
- rlwinm r11,r3,3,(GPR_BYTES-1)*8 // get starting bit position of operand
-#if defined(__ppc__)
- lis r6,hi16(0xFEFEFEFF) // start to generate 32-bit magic constants
+LEXT(strcat) // char* strcat(const char *s, const char *append);
+ andi. r0,r3,3 // is dst aligned?
+ dcbtst 0,r3 // touch in dst
+ lis r6,hi16(0xFEFEFEFF) // start to load magic constants
lis r7,hi16(0x80808080)
- srw r10,r10,r11 // create a mask of 0xFF bytes for operand in r8
+ dcbt 0,r4 // touch in source
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
- srd r10,r10,r11 // create a mask of 0xFF bytes for operand in r8
-#endif
- orc r8,r8,r10 // make sure bytes preceeding operand are nonzero
- b Lword0loopEnter
-
-// Loop over words or doublewords looking for 0-byte marking end of dest.
-// r4 = source ptr (unaligned)
+ mr r9,r3 // use r9 for dest ptr (must return r3 intact)
+ beq Lword0loop // dest is aligned
+ subfic r0,r0,4 // r0 <- #bytes to word align dest
+ mtctr r0
+
+// Loop over bytes looking for 0-byte marking end of dest.
+// r4 = source ptr (unalaigned)
// r6 = 0xFEFEFEFF
// r7 = 0x80808080
-// r9 = dest ptr (aligned)
+// r9 = dest ptr (unaligned)
+// ctr = byte count
+
+Lbyte0loop:
+ lbz r8,0(r9) // r8 <- next dest byte
+ addi r9,r9,1
+ cmpwi r8,0 // test for 0
+ bdnzf eq,Lbyte0loop // loop until (ctr==0) | (r8==0)
+
+ bne Lword0loop // enter word loop if we haven't found the 0-byte
+ subi r9,r9,1 // point to 0-byte
+ b L0found // start to append the source
+
+// Loop over words looking for 0-byte marking end of dest.
+// r4 = source ptr (unalaigned)
+// r6 = 0xFEFEFEFF
+// r7 = 0x80808080
+// r9 = dest ptr (word aligned)
.align 5 // align inner loops for speed
Lword0loop:
- lgu r8,GPR_BYTES(r9) // r8 <- next dest word or doubleword
-Lword0loopEnter: // initial entry
+ lwz r8,0(r9) // r8 <- next dest word
+ addi r9,r9,4
add r10,r8,r6 // r10 <- word + 0xFEFEFEFF
andc r12,r7,r8 // r12 <- ~word & 0x80808080
and. r11,r10,r12 // r11 <- nonzero iff word has a 0-byte
beq Lword0loop // loop until 0 found
-
-// Now we know one of the bytes in r8 is zero, we just have to figure out which one.
-// We have mapped 0 bytes to 0x80, and nonzero bytes to 0x00, with one exception:
-// 0x01 bytes preceeding the first zero are also mapped to 0x80. So we have to mask
-// out the 0x80s caused by 0x01s before searching for the 0x80 byte. Once the 0 is
-// found, we can start appending source. We align the source, which allows us to
-// avoid worrying about spurious page faults.
+
+ slwi r0,r8,7 // move 0x01 bits (false hits) into 0x80 position
+ subi r9,r9,4 // back r9 up to beginning of word
+ andc r11,r11,r0 // mask out false hits
+ cntlzw r0,r11 // find 0 byte (r0 = 0, 8, 16, or 24)
+ srwi r0,r0,3 // now r0 = 0, 1, 2, or 3
+ add r9,r9,r0 // now r9 points to the 0-byte in dest
+
+// End of dest found, so we can start appending source.
+// We align the _source_, which allows us to avoid all worries about
+// spurious page faults. Doing so is faster than aligning the dest.
// r4 = source ptr (unaligned)
// r6 = 0xFEFEFEFF
// r7 = 0x80808080
-// r8 = word or doubleword with a 0-byte
-// r9 = ptr to the word or doubleword in r8 (aligned)
-// r11 = mapped word or doubleword
+// r9 = ptr to 0-byte (unaligned)
- slgi r10,r8,7 // move 0x01 bits (false hits) into 0x80 position
- andi. r0,r4,GPR_BYTES-1 // is source aligned?
- andc r11,r11,r10 // mask out false hits
- cntlzg r10,r11 // find 0 byte (r0 = 0, 8, 16, or 24)
- subfic r0,r0,GPR_BYTES // get #bytes to align r4
- srwi r10,r10,3 // now r0 = 0, 1, 2, or 3
- add r9,r9,r10 // now r9 points to the 0-byte in dest
- beq LwordloopEnter // skip if source is already aligned
-
+L0found:
+ andi. r0,r4,3 // is source aligned?
+ beq LwordloopEnter // skip if so
+ subfic r0,r0,4 // not aligned, get #bytes to align r4
mtctr r0 // set up loop
// Loop over bytes.
@@ -138,31 +135,31 @@
bne LwordloopEnter // 0-byte not found, so enter word loop
blr // 0-byte found, done
-// Word loop: move a word or doubleword at a time until 0-byte found.
-// r4 = source ptr (aligned)
+// Word loop: move a word at a time until 0-byte found.
+// r4 = source ptr (word aligned)
// r6 = 0xFEFEFEFF
// r7 = 0x80808080
// r9 = dest ptr (unaligned)
.align 5 // align inner loop, which is 8 words ling
Lwordloop:
- stg r8,0(r9) // pack word or doubleword into destination
- addi r9,r9,GPR_BYTES
+ stw r8,0(r9) // pack word into destination
+ addi r9,r9,4
LwordloopEnter:
- lg r8,0(r4) // r8 <- next 4 or 8 source bytes
- addi r4,r4,GPR_BYTES
+ 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
and. r0,r10,r12 // r0 <- nonzero iff word has a 0-byte
- beq Lwordloop // loop if no 0-byte
+ beq Lwordloop // loop if ctr!=0 and cr0_eq
// Found a 0-byte. Store last word up to and including the 0, a byte at a time.
-// r8 = last word or doubleword, known to have a 0-byte
+// r8 = last word, known to have a 0-byte
// r9 = dest ptr
Lstorelastbytes:
- srgi. r0,r8,GPR_BYTES*8-8 // shift leftmost byte into bottom so we can "stb"
- slgi r8,r8,8 // move on to next
+ srwi. r0,r8,24 // right justify next byte and test for 0
+ slwi r8,r8,8 // shift next byte into position
stb r0,0(r9) // pack into dest
addi r9,r9,1
bne Lstorelastbytes // loop until 0 stored