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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/alpha/lib/ev67-strncat.S
downloadconfigs-2.6.12-rc2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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+/*
+ * arch/alpha/lib/ev67-strncat.S
+ * 21264 version contributed by Rick Gorton <rick.gorton@api-networks.com>
+ *
+ * Append no more than COUNT characters from the null-terminated string SRC
+ * to the null-terminated string DST. Always null-terminate the new DST.
+ *
+ * This differs slightly from the semantics in libc in that we never write
+ * past count, whereas libc may write to count+1. This follows the generic
+ * implementation in lib/string.c and is, IMHO, more sensible.
+ *
+ * Much of the information about 21264 scheduling/coding comes from:
+ * Compiler Writer's Guide for the Alpha 21264
+ * abbreviated as 'CWG' in other comments here
+ * ftp.digital.com/pub/Digital/info/semiconductor/literature/dsc-library.html
+ * Scheduling notation:
+ * E - either cluster
+ * U - upper subcluster; U0 - subcluster U0; U1 - subcluster U1
+ * L - lower subcluster; L0 - subcluster L0; L1 - subcluster L1
+ * Try not to change the actual algorithm if possible for consistency.
+ */
+
+
+ .text
+
+ .align 4
+ .globl strncat
+ .ent strncat
+strncat:
+ .frame $30, 0, $26
+ .prologue 0
+
+ mov $16, $0 # set up return value
+ beq $18, $zerocount # U :
+ /* Find the end of the string. */
+ ldq_u $1, 0($16) # L : load first quadword ($16 may be misaligned)
+ lda $2, -1($31) # E :
+
+ insqh $2, $0, $2 # U :
+ andnot $16, 7, $16 # E :
+ nop # E :
+ or $2, $1, $1 # E :
+
+ nop # E :
+ nop # E :
+ cmpbge $31, $1, $2 # E : bits set iff byte == 0
+ bne $2, $found # U :
+
+$loop: ldq $1, 8($16) # L :
+ addq $16, 8, $16 # E :
+ cmpbge $31, $1, $2 # E :
+ beq $2, $loop # U :
+
+$found: cttz $2, $3 # U0 :
+ addq $16, $3, $16 # E :
+ nop # E :
+ bsr $23, __stxncpy # L0 :/* Now do the append. */
+
+ /* Worry about the null termination. */
+
+ zapnot $1, $27, $2 # U : was last byte a null?
+ cmplt $27, $24, $5 # E : did we fill the buffer completely?
+ bne $2, 0f # U :
+ ret # L0 :
+
+0: or $5, $18, $2 # E :
+ nop
+ bne $2, 2f # U :
+ and $24, 0x80, $3 # E : no zero next byte
+
+ nop # E :
+ bne $3, 1f # U :
+ /* Here there are bytes left in the current word. Clear one. */
+ addq $24, $24, $24 # E : end-of-count bit <<= 1
+ nop # E :
+
+2: zap $1, $24, $1 # U :
+ nop # E :
+ stq_u $1, 0($16) # L :
+ ret # L0 :
+
+1: /* Here we must clear the first byte of the next DST word */
+ stb $31, 8($16) # L :
+ nop # E :
+ nop # E :
+ ret # L0 :
+
+$zerocount:
+ nop # E :
+ nop # E :
+ nop # E :
+ ret # L0 :
+
+ .end strncat