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123 lines (102 loc) · 2.37 KB
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Copy pathex23.c
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123 lines (102 loc) · 2.37 KB
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#include "dbg.h"
#include "duff.h"
int normal_copy(char *from, char *to, int count) {
int i = 0;
for (i = 0; i < count; i++) {
to[i] = from[i];
}
return i;
}
// for from = {'x'}, to = {'y'}, and count == 1000
// n = 1007 / 8 = 125 ;; count = 1000 ;; count % 8 = 0 ;; from is copied to ;; n = 124 > 0
// n = 124 ;; count = 1000 ;; 0 ;; from copied to ;; n = 123
int duffs_device(char *from, char *to, int count) {
{
int n = (count + 7) / 8;
switch (count % 8) {
case 0:
do {
duff_device();
// *to++ = *from++;
// case 7:
// *to++ = *from++;
// case 6:
// *to++ = *from++;
// case 5:
// *to++ = *from++;
// case 4:
// *to++ = *from++;
// case 3:
// *to++ = *from++;
// case 2:
// *to++ = *from++;
// case 1:
// *to++ = *from++;
} while (--n > 0);
}
}
return count;
}
int zeds_device(char *from, char *to, int count) {
{
int n = (count + 7) / 8;
switch (count % 8) {
case 0:
again:
*to++ = *from++;
case 7:
*to++ = *from++;
case 6:
*to++ = *from++;
case 5:
*to++ = *from++;
case 4:
*to++ = *from++;
case 3:
*to++ = *from++;
case 2:
*to++ = *from++;
case 1:
*to++ = *from++;
if (--n > 0) {
goto again;
}
}
}
return count;
}
int valid_copy(char *data, int count, char expects) {
int i = 0;
for (i = 0; i < count; i++) {
if (data[i] != expects) {
log_err("[%d] %c != %c", i, data[i], expects);
return 0;
}
}
return 1;
}
int main(int argc, char *argv[]) {
char from[1000] = {'a'};
char to[1000] = {'c'};
int rc = 0;
memset(from, 'x', 1000);
memset(to, 'y', 1000);
check(valid_copy(to, 1000, 'y'), "Not initialized right");
rc = normal_copy(from, to, 1000);
check(rc == 1000, "Normal copy failed: %d", rc);
check(valid_copy(to, 1000, 'x'), "Normal copy failed");
// reset
memset(to, 'y', 1000);
rc = duffs_device(from, to, 1000);
check(rc == 1000, "Duff's device failed: %d", rc);
check(valid_copy(to, 1000, 'x'), "Duff's device failed to copy");
// reset
memset(to, 'y', 1000);
// zed
rc = zeds_device(from, to, 1000);
check(rc == 1000, "Zed's device failed: %d", rc);
check(valid_copy(to, 1000, 'x'), "Zed's device failed copy");
return 0;
error:
return 1;
}