upscheme/llt/swapreverse.c

188 lines
4.2 KiB
C

#include <stdlib.h>
#include <string.h>
#include <stddef.h>
#include <alloca.h>
#include "dtypes.h"
#include "utils.h"
void memswap(char *a, char *b, size_t sz)
{
int8_t i8;
int32_t i32;
int32_t *a4, *b4;
if (sz < 4) {
while (sz--) {
i8 = *a;
*a++ = *b;
*b++ = i8;
}
}
else {
while (sz & 0x3) {
i8 = *a;
*a++ = *b;
*b++ = i8;
sz--;
}
a4 = (int32_t*)a;
b4 = (int32_t*)b;
sz >>= 2;
while (sz--) {
i32 = *a4;
*a4++ = *b4;
*b4++ = i32;
}
}
}
void memreverse(char *a, size_t n, size_t elsz)
{
int64_t i64, *pi64;
int32_t i32, *pi32;
int16_t i16, *pi16;
int8_t i8;
size_t i;
char *temp;
size_t eli, tot;
if (n==0 || elsz==0) return;
switch(elsz) {
case 16:
pi64 = (int64_t*)a;
for(i=0; i < n/2; i++) {
i64 = pi64[2*i];
pi64[2*i] = pi64[2*(n-i-1)];
pi64[2*(n-i-1)] = i64;
i64 = pi64[2*i+1];
pi64[2*i+1] = pi64[2*(n-i-1)+1];
pi64[2*(n-i-1)+1] = i64;
}
break;
case 8:
pi64 = (int64_t*)a;
for(i=0; i < n/2; i++) {
i64 = pi64[i];
pi64[i] = pi64[n-i-1];
pi64[n-i-1] = i64;
}
break;
case 4:
pi32 = (int32_t*)a;
for(i=0; i < n/2; i++) {
i32 = pi32[i];
pi32[i] = pi32[n-i-1];
pi32[n-i-1] = i32;
}
break;
case 2:
pi16 = (int16_t*)a;
for(i=0; i < n/2; i++) {
i16 = pi16[i];
pi16[i] = pi16[n-i-1];
pi16[n-i-1] = i16;
}
break;
case 1:
for(i=0; i < n/2; i++) {
i8 = a[i];
a[i] = a[n-i-1];
a[n-i-1] = i8;
}
break;
default:
tot = n*elsz;
if (elsz < 4097)
temp = alloca(elsz);
else
temp = malloc(elsz);
if (temp != NULL) {
for(i=0, eli=0; i < n/2; i++, eli+=elsz) {
memcpy(temp, &a[eli], elsz);
memcpy(&a[eli], &a[tot-eli-elsz], elsz);
memcpy(&a[tot-eli-elsz], temp, elsz);
}
if (elsz >= 4097)
free(temp);
}
break;
}
}
void memreverse_to(char *dest, char *a, size_t n, size_t elsz)
{
int64_t *pi64, *di64;
int32_t *pi32, *di32;
int16_t *pi16, *di16;
size_t i;
size_t eli, tot;
if (n==0 || elsz==0) return;
switch(elsz) {
case 16:
pi64 = (int64_t*)a;
di64 = (int64_t*)dest;
for(i=0; i < n/2; i++) {
di64[2*i] = pi64[2*(n-i-1)];
di64[2*(n-i-1)] = pi64[2*i];
di64[2*i+1] = pi64[2*(n-i-1)+1];
di64[2*(n-i-1)+1] = pi64[2*i+1];
}
if (n&0x1) {
di64[2*i] = pi64[2*i];
di64[2*i+1] = pi64[2*i+1];
}
break;
case 8:
pi64 = (int64_t*)a;
di64 = (int64_t*)dest;
for(i=0; i < n/2; i++) {
di64[i] = pi64[n-i-1];
di64[n-i-1] = pi64[i];
}
if (n&0x1)
di64[i] = pi64[i];
break;
case 4:
pi32 = (int32_t*)a;
di32 = (int32_t*)dest;
for(i=0; i < n/2; i++) {
di32[i] = pi32[n-i-1];
di32[n-i-1] = pi32[i];
}
if (n&0x1)
di32[i] = pi32[i];
break;
case 2:
pi16 = (int16_t*)a;
di16 = (int16_t*)dest;
for(i=0; i < n/2; i++) {
di16[i] = pi16[n-i-1];
di16[n-i-1] = pi16[i];
}
if (n&0x1)
di16[i] = pi16[i];
break;
case 1:
for(i=0; i < n/2; i++) {
dest[i] = a[n-i-1];
dest[n-i-1] = a[i];
}
if (n&0x1)
dest[i] = a[i];
break;
default:
tot = n*elsz;
for(i=0, eli=0; i < n/2; i++, eli+=elsz) {
memcpy(&dest[eli], &a[tot - eli - elsz], elsz);
memcpy(&dest[tot - eli - elsz], &a[eli], elsz);
}
if (n&0x1)
memcpy(&dest[eli], &a[eli], elsz);
break;
}
}