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--- Libc/Libc-320/ppc/string/strncat.s
+++ Libc/Libc-391/ppc/string/strncat.s
@@ -2,8 +2,6 @@
* 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
@@ -26,6 +24,17 @@
#include <mach/ppc/asm.h>
#undef ASSEMBLER
+/* 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>
+
+#define __APPLE_API_PRIVATE
+#include <machine/cpu_capabilities.h>
+#undef __APPLE_API_PRIVATE
+
+
// *****************
// * S T R N C A T *
// *****************
@@ -50,71 +59,70 @@
// Note that "count" refers to the max number of bytes to _append_.
// There is no limit to the number of bytes we will scan looking for
// the end of the "dst" string.
+//
+// In 64-bit mode, this algorithm is doubleword parallel.
.text
.globl EXT(strncat)
.align 5
-LEXT(strncat)
- andi. r0,r3,3 // is dst aligned?
- dcbtst 0,r3 // touch in dst
- lis r6,hi16(0xFEFEFEFF) // start to load magic constants
+LEXT(strncat) // char* strncat(char *dst, const char *src, size_t count);
+ 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
lis r7,hi16(0x80808080)
- dcbt 0,r4 // touch in source
+ srw r10,r10,r11 // create a mask of 0xFF bytes for operand in r8
ori r6,r6,lo16(0xFEFEFEFF)
ori r7,r7,lo16(0x80808080)
- 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 // set up byte loop
-
-// Loop over bytes looking for 0-byte marking end of dest, until dest is
-// word aligned.
+#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)
// r5 = count (unchanged so far)
// r6 = 0xFEFEFEFF
// r7 = 0x80808080
-// 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 // haven't found 0, so enter word-aligned loop
- andi. r0,r4,3 // is source aligned?
- subi r9,r9,1 // point to the 0-byte we just stored
- beq Laligned // source is already aligned
- subfic r0,r0,4 // r0 <- #bytes to word align source
- b Lbyteloop // must align source
-
-// Loop over words looking for 0-byte marking end of dest.
-// r4 = source ptr (unaligned)
-// r5 = count (unchanged so far)
-// r6 = 0xFEFEFEFF
-// r7 = 0x80808080
-// r9 = dest ptr (word aligned)
+// r9 = dest ptr (aligned)
.align 5 // align inner loops for speed
Lword0loop:
- lwz r8,0(r9) // r8 <- next dest word
- addi r9,r9,4
+ lgu r8,GPR_BYTES(r9) // r8 <- next dest word or doubleword
+Lword0loopEnter:
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.
+// r4 = source ptr (unaligned)
+// r5 = count (unchanged so far)
+// 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
- slwi r10,r8,7 // move 0x01 bits (false hits) into 0x80 position
- andi. r0,r4,3 // is source aligned?
+ 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
- subi r9,r9,4 // back up r9 to the start of the word
- cntlzw r10,r11 // find 0 byte (r0 = 0, 8, 16, or 24)
+ 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 r10 = 0, 1, 2, or 3
add r9,r9,r10 // now r9 points to the 0-byte in dest
beq Laligned // skip if source already aligned
- 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)
@@ -125,7 +133,7 @@
// r9 = dest ptr (unaligned)
Lbyteloop:
- cmpwi r5,0 // buffer empty? (note: unsigned)
+ cmpgi r5,0 // buffer empty? (note: count is unsigned)
beq-- L0notfound // buffer full but 0 not found
lbz r8,0(r4) // r8 <- next source byte
subic. r0,r0,1 // decrement count of bytes to move
@@ -137,40 +145,40 @@
beqlr cr1 // byte was 0, so done
bne Lbyteloop // r0!=0, source not yet aligned
-// Source is word aligned. Loop over words until 0-byte found or end
-// of buffer.
-// r4 = source ptr (word aligned)
+// Source is aligned. Loop over words or doublewords until 0-byte found
+// or end of buffer.
+// r4 = source ptr (aligned)
// r5 = length remaining in buffer
// r6 = 0xFEFEFEFF
// r7 = 0x80808080
// r9 = dest ptr (unaligned)
Laligned:
- srwi. r8,r5,2 // get #words in buffer
+ srgi. r8,r5,LOG2_GPR_BYTES// get #words or doublewords in buffer
addi r0,r5,1 // if no words, copy rest of buffer
beq-- Lbyteloop // fewer than 4 bytes in buffer
mtctr r8 // set up word loop count
- rlwinm r5,r5,0,0x3 // mask buffer length down to leftover bytes
+ rlwinm r5,r5,0,GPR_BYTES-1 // mask buffer length down to leftover bytes
b LwordloopEnter
-// Inner loop: move a word at a time, until one of two conditions:
+// Inner loop: move a word or doubleword at a time, until one of two conditions:
// - a zero byte is found
// - end of buffer
// At this point, registers are as follows:
-// r4 = source ptr (word aligned)
-// r5 = bytes leftover in buffer (0..3)
-// r6 = 0xFEFEFEFF
-// r7 = 0x80808080
-// r9 = dest ptr (unaligned)
-// ctr = whole words left in buffer
+// r4 = source ptr (aligned)
+// r5 = bytes leftover in buffer (0..GPR_BYTES-1)
+// r6 = 0xFEFEFEFF
+// r7 = 0x80808080
+// r9 = dest ptr (unaligned)
+// ctr = whole words or doublewords left in buffer
.align 5 // align inner loop, which is 8 words long
Lwordloop:
- stw r8,0(r9) // pack word into destination
- addi r9,r9,4
+ stg r8,0(r9) // pack word or doubleword into destination
+ addi r9,r9,GPR_BYTES
LwordloopEnter:
- lwz r8,0(r4) // r8 <- next 4 source bytes
- addi r4,r4,4
+ lg r8,0(r4) // r8 <- next GPR_BYTES source bytes
+ addi r4,r4,GPR_BYTES
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
@@ -179,12 +187,12 @@
beq-- LcheckLeftovers // skip if 0-byte not found
// Found a 0-byte. Store last word up to and including the 0, a byte at a time.
-// r8 = last word, known to have a 0-byte
+// r8 = last word or doubleword, known to have a 0-byte
// r9 = dest ptr
Lstorelastbytes:
- srwi. r0,r8,24 // right justify next byte and test for 0
- slwi r8,r8,8 // shift next byte into position
+ srgi. r0,r8,GPR_BYTES*8-8 // right justify next byte and test for 0
+ slgi 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
@@ -192,17 +200,17 @@
blr
// 0-byte not found while appending words to source. There might be up to
-// 3 "leftover" bytes to append, hopefully the 0-byte is in there.
+// GPR_BYTES-1 "leftover" bytes to append, hopefully the 0-byte is in there.
// r4 = source ptr (past word in r8)
-// r5 = bytes leftover in buffer (0..3)
-// r6 = 0xFEFEFEFF
-// r7 = 0x80808080
-// r8 = last word of source, with no 0-byte
+// r5 = bytes leftover in buffer (0..GPR_BYTES-1)
+// r6 = 0xFEFEFEFF
+// r7 = 0x80808080
+// r8 = last word or doubleword of source, with no 0-byte
// r9 = dest ptr (unaligned)
LcheckLeftovers:
- stw r8,0(r9) // store last whole word of source
- addi r9,r9,4
+ stg r8,0(r9) // store last whole word or doubleword of source
+ addi r9,r9,GPR_BYTES
addi r0,r5,1 // let r5 (not r0) terminate byte loop
b Lbyteloop // append last few bytes