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#****************************************************************************
#* *
#* Copyright (c) 1991 by *
#* DIGITAL EQUIPMENT CORPORATION, Maynard, Massachusetts. *
#* All rights reserved. *
#* *
#* This software is furnished under a license and may be used and copied *
#* only in accordance with the terms of such license and with the *
#* inclusion of the above copyright notice. This software or any other *
#* copies thereof may not be provided or otherwise made available to any *
#* other person. No title to and ownership of the software is hereby *
#* transferred. *
#* *
#* The information in this software is subject to change without notice *
#* and should not be construed as a commitment by Digital Equipment *
#* Corporation. *
#* *
#* Digital assumes no responsibility for the use or reliability of its *
#* software on equipment which is not supplied by Digital. *
#* *
#* *
#****************************************************************************
#
#++
# Facility:
# DEC C Run Time Library on the Alpha/WNT Platform
#
# Abstract:
#
# Implements the C RTL function strcpy() for the compiler intrinsic.
#
# Author:
# Bill Noyce 9-Aug-1991
#
# Modified by:
#
# 001 Kevin Routley 10-Sep-1991
# Modified to C RTL Coding standards.
#
# 002 Chris Bord 30 September 1991
# Add decc$ prefixes.
#
# 003 Chris Bord 24 January 1992
# Add second parameter to .procedure_descriptor directive
#
# 004 John Parks 22 January 1993
# Ported to Alpha/NT.
#--
.globl _Otsstrcpy
.ent _Otsstrcpy
# r16 = dst
# r17 = src
# returns r0 = src
# destroys r16-r21, r27-r28
_Otsstrcpy:
.set noat
.set noreorder
ldq_u $27, ($17) # Get first src QW
and $16, 7, $28 #/ Is dst aligned?
lda $18, -1($31) # Get a mask of all 1's
bne $28, dst_unaligned #/ Go handle unaligned dst
and $17, 7, $19 # Is src aligned too?
nop
mov $16, $0 # Set up function result
bne $19, src_unaligned #/ Go handle aligned dst, unaligned src
a_loop:
cmpbge $31, $27, $18 # Any nulls in src QW?
bne $18, a_exit_1 # Finish up if so
ldq $21, 8($17) # Load next QW if not
match: # Enter if src matches unaligned dst
addq $17, 16, $17 #/ Update src pointer for unrolled loop
stq_u $27, ($16) # Store a whole QW
addq $16, 16, $16 #/ Update dst pointer for unrolled loop
cmpbge $31, $21, $18 # Any nulls in src QW?
bne $18, a_exit_2 # Finish up if so
ldq $27, ($17) # Load next QW if not
stq_u $21, -8($16) # Store a whole QW
br $31, a_loop # Repeat during load latency
a_exit_1:
ldq_u $21, ($16) # Get dst QW to update
subq $18, 1, $17 #/ Use location of null byte...
xor $18, $17, $18 # ... to compute mask of what to keep
zapnot $27, $18, $27 # Keep src up to & including null
zap $21, $18, $21 # Make room for new data
nop
or $21, $27, $21 # Combine src & dst...
stq_u $21, ($16) #/ ... and store
ret $31, ($26)
nop
a_exit_2:
ldq_u $27, -8($16) # Get dst QW to update
subq $18, 1, $17 #/ Use location of null byte...
xor $18, $17, $18 # ... to compute mask of what to keep
zapnot $21, $18, $21 # Keep src up to & including null
zap $27, $18, $27 # Make room for new data
nop
or $27, $21, $27 # Combine src & dst...
stq_u $27, -8($16) #/ ... and store
ret $31, ($26)
src_unaligned: # dst_unaligned code would work; is this faster?
mskqh $18, $17, $18 # Zeros where src to be ignored
ornot $27, $18, $19 # Make ignored bytes nonzero
cmpbge $31, $19, $21 # Any null bytes in src data?
extql $27, $17, $27 # Move src to position of dst
bne $21, short_ld #/ Finish up if nulls seen
ldq_u $19, 8($17) # Next src QW needed to fill dst
br $31, u_entry_2 # Enter loop for mismatched alignment
# Here's the hard part. Enter with
# r16 = dst address
# r17 = src address
# r18 = -1
# r27 = first src QW
# r28 = dst alignment (>0)
# Check whether the first src QW has any nulls, and load the next one.
# Combine these if needed to fill the first dst QW, and enter a loop
# that fetches src QWs and checks them, while storing dst QWs.
dst_unaligned:
ldq_u $20, ($16) # Load dst to be updated
mskqh $18, $17, $18 #/ Zeros where src to be ignored
mov $16, $0 # Set up function result
ornot $27, $18, $19 # Make ignored bytes of src nonzero
cmpbge $31, $19, $21 # Any null bytes in src data?
extql $27, $17, $27 # Get only interesting src data
bne $21, short # Finish up if nulls seen
mskql $20, $16, $20 #/ Make room in dst
ldq_u $21, 8($17) # Load next src QW if no nulls
mskql $18, $16, $18 #/ Need two src QWs for first dst QW?
insql $27, $16, $27 # Move src data to position of dst
subq $17, $28, $17 # Adjust src ptr for partial move
and $17, 7, $28 # Is src now aligned?
bne $18, u_loop #/ Enter loop if one src QW fills dst
or $27, $20, $27 # Combine first src QW with dst
extqh $21, $17, $20 # Position 2nd src QW in 1st dst QW
cmpbge $31, $21, $18 # Any nulls in next src QW?
beq $28, match #/ If src aligned, use quick loop
mov $21, $19 # Put src QW where loop expects
bne $18, short_a #/ Finish up if nulls seen
# r16 = address of next dst to store
# r17 = address-16 of next src to load
# r18
# r19 = last loaded src QW
# r20 = one piece of dst QW
# r21
# r27 = other piece of dst QW
# r28
u_loop:
ldq_u $28, 16($17) # Load another src QW
addq $17, 16, $17 #/ Update src pointer for unrolled loop
or $27, $20, $27 # Combine pieces
extql $19, $17, $20 # Get second part of prior src QW
stq_u $27, ($16) # Store a dst QW
cmpbge $31, $28, $19 #/ Any nulls in this src QW?
extqh $28, $17, $27 # Get first part of this src QW
bne $19, u_exit_2 #/ Finish up if nulls seen
ldq_u $19, 8($17) # Load another src QW
addq $16, 16, $16 #/ Update dst pointer for unrolled loop
or $27, $20, $20 # Combine pieces
extql $28, $17, $27 # Get second piece of prior src QW
stq_u $20, -8($16) # Store a dst QW
u_entry_2:
cmpbge $31, $19, $28 #/ Any nulls in this src QW?
extqh $19, $17, $20 # Get first part of this src QW
beq $28, u_loop #/ Repeat if no nulls seen
subq $16, 8, $16 # Undo part of pointer update
mov $19, $28 # Move src QW to expected place
u_exit_2:
or $27, $20, $27 # Combine pieces
ldq_u $18, 8($16) #/ Load dst to update
cmpbge $31, $27, $21 # Is null in first dst QW?
bne $21, u_exit_3 # Skip if so
stq_u $27, 8($16) # Store a whole dst QW
extql $28, $17, $27 #/ Get second part of src QW
ldq_u $18, 16($16) # We'll update next dst QW
cmpbge $31, $27, $21 # Find location of null there
addq $16, 8, $16 # Update dst pointer
u_exit_3:
subq $21, 1, $28 # Using position of null byte...
xor $21, $28, $21 # ... make mask for desired src data
zapnot $27, $21, $27 # Trim src data after null
zap $18, $21, $18 # Make room for it in dst
nop
or $27, $18, $27 # Combine pieces
stq_u $27, 8($16) #/ Store dst QW
ret $31, ($26)
short_ld:
ldq_u $20, ($16) # Load dst QW to update
short:
cmpbge $31, $27, $17 #/ Get mask showing location of null
insql $27, $16, $18 # Move src data to position of dst
mskql $20, $16, $19 # Get dst bytes preceding string
sll $17, $28, $17 # Move mask in the same way
or $18, $19, $18 # Combine src & dst
and $17, 255, $28 # Null byte in first dst QW?
subq $17, 1, $19 # Using position of null byte...
xor $17, $19, $17 # ... make mask for desired src data
bne $28, short_2 #/ Skip if null in first dst QW
ldq_u $20, 8($16) # Load second dst QW
srl $17, 8, $17 #/ Move mask down for use
stq_u $18, ($16) # Store first dst QW
insqh $27, $16, $18 #/ Move src data to position of dst
addq $16, 8, $16 # Advance dst pointer
short_2:
zap $20, $17, $20 # Preserve dst data following null
zapnot $18, $17, $18 # Trim src data after null
nop
or $18, $20, $18 # Combine pieces
stq_u $18, ($16) #/ Store dst QW
ret $31, ($26)
# r16 = dst address
# r17 = updated src address
# r18 = null position
# r19 = next src QW
# r20 = first part of r19, positioned for dst
# r21
# r27 = dst QW so far
# r28 = low bits of updated src address
short_a:
sll $18, 8, $18 # Shift location of null byte...
ldq_u $21, ($16) #/ Reload first dst QW
or $27, $20, $27 # Combine pieces
srl $18, $28, $18 # ... to position in dst QW's
nop
and $18, 255, $20 # Is null in first dst QW?
subq $18, 1, $28 # Using position of null byte...
xor $18, $28, $18 # ... make mask for desired src data
bne $20, short_a1 #/ Skip if null in first QW
stq_u $27, ($16) # Store a whole dst QW
extql $19, $17, $27 #/ Prepare next piece of src
ldq_u $21, 8($16) # Load second dst QW for update
srl $18, 8, $18 #/ Look at next 8 bits of mask
addq $16, 8, $16 # Update dst pointer
short_a1:
zapnot $27, $18, $27 # Keep src data
zap $21, $18, $21 # Keep end of dst QW
nop
or $27, $21, $27 # Combine pieces
stq_u $27, ($16) # Store last dst QW
ret $31, ($26)
.set at
.set reorder
.end _Otsstrcpy
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