--- /dev/null
+/* Copyright (C) 2000 Free Software Foundation, Inc.
+ Contributed by Richard Henderson (rth@tamu.edu)
+ EV6 optimized by Rick Gorton <rick.gorton@alpha-processor.com>.
+
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Library General Public License as
+ published by the Free Software Foundation; either version 2 of the
+ License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Library General Public License for more details.
+
+ You should have received a copy of the GNU Library General Public
+ License along with the GNU C Library; see the file COPYING.LIB. If not,
+ write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA. */
+
+/* Copy no more than COUNT bytes of the null-terminated string from
+ SRC to DST.
+
+ This is an internal routine used by strncpy, stpncpy, and strncat.
+ As such, it uses special linkage conventions to make implementation
+ of these public functions more efficient.
+
+ On input:
+ t9 = return address
+ a0 = DST
+ a1 = SRC
+ a2 = COUNT
+
+ Furthermore, COUNT may not be zero.
+
+ On output:
+ t0 = last word written
+ t8 = bitmask (with one bit set) indicating the last byte written
+ t10 = bitmask (with one bit set) indicating the byte position of
+ the end of the range specified by COUNT
+ a0 = unaligned address of the last *word* written
+ a2 = the number of full words left in COUNT
+
+ Furthermore, v0, a3-a5, t11, and t12 are untouched.
+*/
+
+#include <sysdep.h>
+
+ .arch ev6
+ .set noat
+ .set noreorder
+
+/* There is a problem with either gdb (as of 4.16) or gas (as of 2.7) that
+ doesn't like putting the entry point for a procedure somewhere in the
+ middle of the procedure descriptor. Work around this by putting the
+ aligned copy in its own procedure descriptor */
+
+
+ .ent stxncpy_aligned
+ .align 4
+stxncpy_aligned:
+ .frame sp, 0, t9, 0
+ .prologue 0
+
+ /* On entry to this basic block:
+ t0 == the first destination word for masking back in
+ t1 == the first source word. */
+
+ /* Create the 1st output word and detect 0's in the 1st input word. */
+ lda t2, -1 # E : build a mask against false zero
+ mskqh t2, a1, t2 # U : detection in the src word (stall)
+ mskqh t1, a1, t3 # U :
+ ornot t1, t2, t2 # E : (stall)
+
+ mskql t0, a1, t0 # U : assemble the first output word
+ cmpbge zero, t2, t7 # E : bits set iff null found
+ or t0, t3, t0 # E : (stall)
+ beq a2, $a_eoc # U :
+
+ bne t7, $a_eos # U :
+ nop
+ nop
+ nop
+
+ /* On entry to this basic block:
+ t0 == a source word not containing a null. */
+
+ /*
+ * nops here to:
+ * separate store quads from load quads
+ * limit of 1 bcond/quad to permit training
+ */
+$a_loop:
+ stq_u t0, 0(a0) # L :
+ addq a0, 8, a0 # E :
+ subq a2, 1, a2 # E :
+ nop
+
+ ldq_u t0, 0(a1) # L :
+ addq a1, 8, a1 # E :
+ cmpbge zero, t0, t7 # E :
+ beq a2, $a_eoc # U :
+
+ beq t7, $a_loop # U :
+ nop
+ nop
+ nop
+
+ /* Take care of the final (partial) word store. At this point
+ the end-of-count bit is set in t7 iff it applies.
+
+ On entry to this basic block we have:
+ t0 == the source word containing the null
+ t7 == the cmpbge mask that found it. */
+
+$a_eos:
+ negq t7, t8 # E : find low bit set
+ and t7, t8, t8 # E : (stall)
+ /* For the sake of the cache, don't read a destination word
+ if we're not going to need it. */
+ and t8, 0x80, t6 # E : (stall)
+ bne t6, 1f # U : (stall)
+
+ /* We're doing a partial word store and so need to combine
+ our source and original destination words. */
+ ldq_u t1, 0(a0) # L :
+ subq t8, 1, t6 # E :
+ or t8, t6, t7 # E : (stall)
+ zapnot t0, t7, t0 # U : clear src bytes > null (stall)
+
+ zap t1, t7, t1 # .. e1 : clear dst bytes <= null
+ or t0, t1, t0 # e1 : (stall)
+ nop
+ nop
+
+1: stq_u t0, 0(a0) # L :
+ ret (t9) # L0 : Latency=3
+ nop
+ nop
+
+ /* Add the end-of-count bit to the eos detection bitmask. */
+$a_eoc:
+ or t10, t7, t7 # E :
+ br $a_eos # L0 : Latency=3
+ nop
+ nop
+
+ .end stxncpy_aligned
+
+ .align 4
+ .ent __stxncpy
+ .globl __stxncpy
+__stxncpy:
+ .frame sp, 0, t9, 0
+ .prologue 0
+
+ /* Are source and destination co-aligned? */
+ xor a0, a1, t1 # E :
+ and a0, 7, t0 # E : find dest misalignment
+ and t1, 7, t1 # E : (stall)
+ addq a2, t0, a2 # E : bias count by dest misalignment (stall)
+
+ subq a2, 1, a2 # E :
+ and a2, 7, t2 # E : (stall)
+ srl a2, 3, a2 # U : a2 = loop counter = (count - 1)/8 (stall)
+ addq zero, 1, t10 # E :
+
+ sll t10, t2, t10 # U : t10 = bitmask of last count byte
+ bne t1, $unaligned # U :
+ /* We are co-aligned; take care of a partial first word. */
+ ldq_u t1, 0(a1) # L : load first src word
+ addq a1, 8, a1 # E :
+
+ beq t0, stxncpy_aligned # U : avoid loading dest word if not needed
+ ldq_u t0, 0(a0) # L :
+ nop
+ nop
+
+ br stxncpy_aligned # .. e1 :
+ nop
+ nop
+ nop
+
+
+
+/* The source and destination are not co-aligned. Align the destination
+ and cope. We have to be very careful about not reading too much and
+ causing a SEGV. */
+
+ .align 4
+$u_head:
+ /* We know just enough now to be able to assemble the first
+ full source word. We can still find a zero at the end of it
+ that prevents us from outputting the whole thing.
+
+ On entry to this basic block:
+ t0 == the first dest word, unmasked
+ t1 == the shifted low bits of the first source word
+ t6 == bytemask that is -1 in dest word bytes */
+
+ ldq_u t2, 8(a1) # L : Latency=3 load second src word
+ addq a1, 8, a1 # E :
+ mskql t0, a0, t0 # U : mask trailing garbage in dst
+ extqh t2, a1, t4 # U : (3 cycle stall on t2)
+
+ or t1, t4, t1 # E : first aligned src word complete (stall)
+ mskqh t1, a0, t1 # U : mask leading garbage in src (stall)
+ or t0, t1, t0 # E : first output word complete (stall)
+ or t0, t6, t6 # E : mask original data for zero test (stall)
+
+ cmpbge zero, t6, t7 # E :
+ beq a2, $u_eocfin # U :
+ nop
+ nop
+
+ bne t7, $u_final # U :
+ lda t6, -1 # E : mask out the bits we have
+ mskql t6, a1, t6 # U : already seen (stall)
+ stq_u t0, 0(a0) # L : store first output word
+
+ or t6, t2, t2 # E :
+ cmpbge zero, t2, t7 # E : find nulls in second partial (stall)
+ addq a0, 8, a0 # E :
+ subq a2, 1, a2 # E :
+
+ bne t7, $u_late_head_exit # U :
+ /* Finally, we've got all the stupid leading edge cases taken care
+ of and we can set up to enter the main loop. */
+ extql t2, a1, t1 # U : position hi-bits of lo word
+ ldq_u t2, 8(a1) # L : read next high-order source word
+ addq a1, 8, a1 # E :
+
+ cmpbge zero, t2, t7 # E : (stall)
+ beq a2, $u_eoc # U :
+ nop
+ nop
+
+ bne t7, $u_eos # e1 :
+ nop
+ nop
+ nop
+
+ /* Unaligned copy main loop. In order to avoid reading too much,
+ the loop is structured to detect zeros in aligned source words.
+ This has, unfortunately, effectively pulled half of a loop
+ iteration out into the head and half into the tail, but it does
+ prevent nastiness from accumulating in the very thing we want
+ to run as fast as possible.
+
+ On entry to this basic block:
+ t1 == the shifted high-order bits from the previous source word
+ t2 == the unshifted current source word
+
+ We further know that t2 does not contain a null terminator. */
+
+ .align 4
+$u_loop:
+ extqh t2, a1, t0 # U : extract high bits for current word
+ addq a1, 8, a1 # E :
+ extql t2, a1, t3 # U : extract low bits for next time
+ addq a0, 8, a0 # E :
+
+ or t0, t1, t0 # E : current dst word now complete
+ ldq_u t2, 0(a1) # U : Latency=3 load high word for next time
+ stq_u t0, -8(a0) # U : save the current word (stall)
+ mov t3, t1 # E :
+
+ subq a2, 1, a2 # E :
+ cmpbge zero, t2, t7 # E : test new word for eos (2 cycle stall for data)
+ beq a2, $u_eoc # U : (stall)
+ nop
+
+ beq t7, $u_loop # U :
+ nop
+ nop
+ nop
+
+ /* We've found a zero somewhere in the source word we just read.
+ If it resides in the lower half, we have one (probably partial)
+ word to write out, and if it resides in the upper half, we
+ have one full and one partial word left to write out.
+
+ On entry to this basic block:
+ t1 == the shifted high-order bits from the previous source word
+ t2 == the unshifted current source word. */
+$u_eos:
+ extqh t2, a1, t0 # U :
+ or t0, t1, t0 # E : first (partial) source word complete (stall)
+ cmpbge zero, t0, t7 # E : is the null in this first bit? (stall)
+ bne t7, $u_final # U : (stall)
+
+ stq_u t0, 0(a0) # L : the null was in the high-order bits
+ addq a0, 8, a0 # E :
+ subq a2, 1, a2 # E :
+ nop
+
+$u_late_head_exit:
+ extql t2, a1, t0 # U :
+ cmpbge zero, t0, t7 # E :
+ or t7, t10, t6 # E : (stall)
+ cmoveq a2, t6, t7 # E : Latency=2, extra map slot (stall)
+
+ /* Take care of a final (probably partial) result word.
+ On entry to this basic block:
+ t0 == assembled source word
+ t7 == cmpbge mask that found the null. */
+$u_final:
+ negq t7, t6 # E : isolate low bit set
+ and t6, t7, t8 # E : (stall)
+ and t8, 0x80, t6 # E : avoid dest word load if we can (stall)
+ bne t6, 1f # U : (stall)
+
+ ldq_u t1, 0(a0) # L :
+ subq t8, 1, t6 # E :
+ or t6, t8, t7 # E : (stall)
+ zapnot t0, t7, t0 # U : kill source bytes > null
+
+ zap t1, t7, t1 # U : kill dest bytes <= null
+ or t0, t1, t0 # E : (stall)
+ nop
+ nop
+
+1: stq_u t0, 0(a0) # L :
+ ret (t9) # L0 : Latency=3
+
+$u_eoc: # end-of-count
+ extqh t2, a1, t0 # U :
+ or t0, t1, t0 # E : (stall)
+ cmpbge zero, t0, t7 # E : (stall)
+ nop
+
+$u_eocfin: # end-of-count, final word
+ or t10, t7, t7 # E :
+ br $u_final # L0 : Latency=3
+ nop
+ nop
+
+ /* Unaligned copy entry point. */
+ .align 4
+$unaligned:
+
+ ldq_u t1, 0(a1) # L : load first source word
+ and a0, 7, t4 # E : find dest misalignment
+ and a1, 7, t5 # E : find src misalignment
+ /* Conditionally load the first destination word and a bytemask
+ with 0xff indicating that the destination byte is sacrosanct. */
+ mov zero, t0 # E :
+
+ mov zero, t6 # E :
+ beq t4, 1f # U :
+ ldq_u t0, 0(a0) # L :
+ lda t6, -1 # E :
+
+ mskql t6, a0, t6 # U :
+ nop
+ nop
+ nop
+1:
+ subq a1, t4, a1 # E : sub dest misalignment from src addr
+
+ /* If source misalignment is larger than dest misalignment, we need
+ extra startup checks to avoid SEGV. */
+
+ cmplt t4, t5, t8 # E :
+ extql t1, a1, t1 # U : shift src into place
+ lda t2, -1 # E : for creating masks later
+ beq t8, $u_head # U : (stall)
+
+ mskqh t2, t5, t2 # U : begin src byte validity mask
+ cmpbge zero, t1, t7 # E : is there a zero?
+ extql t2, a1, t2 # U :
+ or t7, t10, t5 # E : test for end-of-count too
+
+ cmpbge zero, t2, t3 # E :
+ cmoveq a2, t5, t7 # E : Latency=2, extra map slot
+ nop # E : keep with cmoveq
+ andnot t7, t3, t7 # E : (stall)
+
+ beq t7, $u_head # U :
+ /* At this point we've found a zero in the first partial word of
+ the source. We need to isolate the valid source data and mask
+ it into the original destination data. (Incidentally, we know
+ that we'll need at least one byte of that original dest word.) */
+ ldq_u t0, 0(a0) # L :
+ negq t7, t6 # E : build bitmask of bytes <= zero
+ mskqh t1, t4, t1 # U :
+
+ and t6, t7, t8 # E :
+ subq t8, 1, t6 # E : (stall)
+ or t6, t8, t7 # E : (stall)
+ zapnot t2, t7, t2 # U : prepare source word; mirror changes (stall)
+
+ zapnot t1, t7, t1 # U : to source validity mask
+ andnot t0, t2, t0 # E : zero place for source to reside
+ or t0, t1, t0 # E : and put it there (stall both t0, t1)
+ stq_u t0, 0(a0) # L : (stall)
+
+ ret (t9) # L0 : Latency=3
+ nop
+ nop
+ nop
+
+ .end __stxncpy
+
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