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Atari Mega Archive 1
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bcopy.cpp
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C/C++ Source or Header
|
1993-01-22
|
5KB
|
238 lines
| new version of bcopy, memcpy and memmove
| handles overlap, odd/even alignment
| uses movem to copy 256 bytes blocks faster.
| Alexander Lehmann alexlehm@iti.informatik.th-darmstadt.de
| sortof inspired by jrbs bcopy
.text
.even
.globl _bcopy
.globl __bcopy
.globl _memcpy
.globl _memmove
| void *memcpy( void *dest, const void *src, size_t len );
| void *memmove( void *dest, const void *src, size_t len );
| returns dest
| functions are aliased
#ifndef __SOZOBON__
_memcpy:
_memmove:
movl sp@(4),a1 | dest
movl sp@(8),a0 | src
jra common | the rest is samea as bcopy
#else
| _bcopy() is the base function below; for memcpy(), memmove()
| and bcopy(), we have to sneak a size_t into an unsigned long first.
_memcpy:
_memmove:
movl sp@(4),a1 | dest
movl sp@(8),a0 | src
clrl d0 | here is the sneaky bit...
movw sp@(12),d0 | length
jra common2 | the rest is samea as bcopy
_bcopy:
movl sp@(4),a0 | src
movl sp@(8),a1 | dest
clrl d0 | here is the sneaky bit...
movw sp@(12),d0 | length
jra common2 | the rest is samea as bcopy
#endif
| void bcopy( const void *src, void *dest, size_t length );
| void _bcopy( const void *src, void *dest, unsigned long length );
| return value not used (returns src)
| functions are aliased (except for HSC -- sb)
#ifndef __SOZOBON__
_bcopy:
#endif
__bcopy:
movl sp@(4),a0 | src
movl sp@(8),a1 | dest
common: movl sp@(12),d0 | length
common2:
jeq exit | length==0? (size_t)
| a0 src, a1 dest, d0.l length
movel d2,sp@-
| overlay ?
cmpl a0,a1
jgt top_down
movw a0,d1 | test for alignment
movw a1,d2
eorw d2,d1
btst #0,d1 | one odd one even ?
jne slow_copy
btst #0,d2 | both even ?
jeq both_even
movb a0@+,a1@+ | copy one byte, now we are both even
subql #1,d0
both_even:
clrw d1 | save length less 256
movb d0,d1
lsrl #8,d0 | number of 256 bytes blocks
jeq less256
movml d1/d3-d7/a2/a3/a5/a6,sp@- | d2 is already saved
| exclude a4 because of -mbaserel
copy256:
movml a0@+,d1-d7/a2/a3/a5/a6 | copy 5*44+36=256 bytes
movml d1-d7/a2/a3/a5/a6,a1@
movml a0@+,d1-d7/a2/a3/a5/a6
movml d1-d7/a2/a3/a5/a6,a1@(44)
movml a0@+,d1-d7/a2/a3/a5/a6
movml d1-d7/a2/a3/a5/a6,a1@(88)
movml a0@+,d1-d7/a2/a3/a5/a6
movml d1-d7/a2/a3/a5/a6,a1@(132)
movml a0@+,d1-d7/a2/a3/a5/a6
movml d1-d7/a2/a3/a5/a6,a1@(176)
movml a0@+,d1-d7/a2-a3
movml d1-d7/a2-a3,a1@(220)
lea a1@(256),a1 | increment dest, src is already
subql #1,d0
jne copy256 | next, please
movml sp@+,d1/d3-d7/a2/a3/a5/a6
less256: | copy 16 bytes blocks
movw d1,d0
lsrw #2,d0 | number of 4 bytes blocks
jeq less4 | less that 4 bytes left
movw d0,d2
negw d2
andw #3,d2 | d2 = number of bytes below 16 (-n)&3
subqw #1,d0
lsrw #2,d0 | number of 16 bytes blocks minus 1, if d2==0
addw d2,d2 | offset in code (movl two bytes)
jmp pc@(2,d2:w) | jmp into loop
copy16:
movl a0@+,a1@+
movl a0@+,a1@+
movl a0@+,a1@+
movl a0@+,a1@+
dbra d0,copy16
less4:
btst #1,d1
jeq less2
movw a0@+,a1@+
less2:
btst #0,d1
jeq none
movb a0@,a1@
none:
exit_d2:
movl sp@+,d2
exit:
movl sp@(4),d0 | return dest (for memcpy only)
rts
slow_copy: | byte by bytes copy
movw d0,d1
negw d1
andw #7,d1 | d1 = number of bytes blow 8 (-n)&7
addql #7,d0
lsrl #3,d0 | number of 8 bytes block plus 1, if d1!=0
addw d1,d1 | offset in code (movb two bytes)
jmp pc@(2,d1:w) | jump into loop
scopy:
movb a0@+,a1@+
movb a0@+,a1@+
movb a0@+,a1@+
movb a0@+,a1@+
movb a0@+,a1@+
movb a0@+,a1@+
movb a0@+,a1@+
movb a0@+,a1@+
subql #1,d0
jne scopy
jra exit_d2
top_down:
addl d0,a0 | a0 byte after end of src
addl d0,a1 | a1 byte after end of dest
movw a0,d1 | exact the same as above, only with predec
movw a1,d2
eorw d2,d1
btst #0,d1
jne slow_copy_d
btst #0,d2
jeq both_even_d
movb a0@-,a1@-
subql #1,d0
both_even_d:
clrw d1
movb d0,d1
lsrl #8,d0
jeq less256_d
movml d1/d3-d7/a2/a3/a5/a6,sp@-
copy256_d:
movml a0@(-44),d1-d7/a2/a3/a5/a6
movml d1-d7/a2/a3/a5/a6,a1@-
movml a0@(-88),d1-d7/a2/a3/a5/a6
movml d1-d7/a2/a3/a5/a6,a1@-
movml a0@(-132),d1-d7/a2/a3/a5/a6
movml d1-d7/a2/a3/a5/a6,a1@-
movml a0@(-176),d1-d7/a2/a3/a5/a6
movml d1-d7/a2/a3/a5/a6,a1@-
movml a0@(-220),d1-d7/a2/a3/a5/a6
movml d1-d7/a2/a3/a5/a6,a1@-
movml a0@(-256),d1-d7/a2-a3
movml d1-d7/a2-a3,a1@-
lea a0@(-256),a0
subql #1,d0
jne copy256_d
movml sp@+,d1/d3-d7/a2/a3/a5/a6
less256_d:
movw d1,d0
lsrw #2,d0
jeq less4_d
movw d0,d2
negw d2
andw #3,d2
subqw #1,d0
lsrw #2,d0
addw d2,d2
jmp pc@(2,d2:w)
copy16_d:
movl a0@-,a1@-
movl a0@-,a1@-
movl a0@-,a1@-
movl a0@-,a1@-
dbra d0,copy16_d
less4_d:
btst #1,d1
jeq less2_d
movw a0@-,a1@-
less2_d:
btst #0,d1
jeq exit_d2
movb a0@-,a1@-
jra exit_d2
slow_copy_d:
movw d0,d1
negw d1
andw #7,d1
addql #7,d0
lsrl #3,d0
addw d1,d1
jmp pc@(2,d1:w)
scopy_d:
movb a0@-,a1@-
movb a0@-,a1@-
movb a0@-,a1@-
movb a0@-,a1@-
movb a0@-,a1@-
movb a0@-,a1@-
movb a0@-,a1@-
movb a0@-,a1@-
subql #1,d0
jne scopy_d
jra exit_d2