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[/] [forwardcom/] [libraries/] [memcpy.as] - Rev 108
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/********************************* memcpy.as ********************************
* Author: Agner Fog
* date created: 2018-03-25
* Last modified: 2021-04-25
* Version: 1.11
* Project: ForwardCom library libc.li
* Description: memcpy and memmove functions. Copy memory block
* C declaration: void *memcpy (void *dest, const void *src, uint64_t n)
* C declaration: void *memmove(void *dest, const void *src, uint64_t n)
*
* Copyright 2018-2021 GNU General Public License http://www.gnu.org/licenses
*****************************************************************************/
// ! To do: Make vector read and write aligned for better performance
public _memcpy: function, reguse = 0x1F, 1
public _memmove: function, reguse = 0x1F, 1
code section execute align = 4
// r0 = destination
// r1 = source
// r2 = n
_memcpy function
_memmove:
int64 r3 = r0 - r1
if (uint64 r3 >= r2) {
// destination will not overwrite source. copy forwards
int64 r3 = r0 + r2 // end of destination
int64 r4 = r1 + r2 // end of source
// vector loop. count down r2
for (int8 v0 in [r3-r2]) {
int8 v0 = [r4-r2, length = r2] // read from source
int8 [r3-r2, length = r2] = v0 // write to destination
}
}
else {
// destination overlaps source. copy backwards
push (r0) // save destination
int8 v0 = set_len(v0, r2) // length = min(n,maxlen)
int64 r3 = get_len(v0) // this will be the block size
int64 r0 = r0 + r2 - r3 // last block of destination
int64 r1 = r1 + r2 - r3 // last block of source
int64 r4 = r3 // current block size
while (uint64 r2 > 0) { // loop counting down remaining bytes
int8 v0 = [r1, length = r4] // read from source
int8 [r0, length = r4] = v0 // write to destination
int64 r2 -= r4 // subtract block size from remaining size
uint64 r4 = min_u(r2, r3) // block size = minimum of remaining bytes and maxlen
int64 r0 -= r4 // subtract next block size from destination
int64 r1 -= r4 // subtract next block size from source
}
pop (r0) // restore destination
}
return // return dest in r0 unchanged
_memcpy end
code end
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