110 lines
2.2 KiB
C
110 lines
2.2 KiB
C
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#include <stdio.h>
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#include <string.h>
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#include "dbg.h"
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int normal_copy(char *from, char *to, int count)
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{
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int i = 0;
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for(i = 0; i < count; i++) {
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to[i] = from[i];
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}
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return i;
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}
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int duffs_device(char *from, char *to, int count)
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{
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{
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int n = (count + 7) / 8;
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debug("n=%d, (count %% 8)=%d", n, count % 8);
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switch(count % 8) {
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case 0: do { *to++ = *from++;
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case 7: *to++ = *from++;
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case 6: *to++ = *from++;
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case 5: *to++ = *from++;
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case 4: *to++ = *from++;
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case 3: *to++ = *from++;
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case 2: *to++ = *from++;
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case 1: *to++ = *from++;
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} while(--n > 0);
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}
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}
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return count;
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}
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int zeds_device(char *from, char *to, int count)
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{
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{
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int n = (count + 7) / 8;
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switch(count % 8) {
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case 0:
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again: *to++ = *from++;
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case 7: *to++ = *from++;
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case 6: *to++ = *from++;
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case 5: *to++ = *from++;
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case 4: *to++ = *from++;
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case 3: *to++ = *from++;
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case 2: *to++ = *from++;
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case 1: *to++ = *from++;
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if(--n > 0) goto again;
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}
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}
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return count;
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}
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int valid_copy(char *data, int count, char expects)
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{
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int i = 0;
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for(i = 0; i < count; i++) {
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if(data[i] != expects) {
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log_err("[%d] %c != %c", i, data[i], expects);
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return 0;
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}
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}
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return 1;
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}
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int main(int argc, char *argv[])
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{
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char from[1000] = {'a'};
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char to[1000] = {'c'};
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int rc = 0;
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// setup the from to have some stuff
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memset(from, 'x', 1000);
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// set it to a failure mode
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memset(to, 'y', 1000);
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check(valid_copy(to, 1000, 'y'), "Not initialized right.");
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// use normal copy to
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rc = normal_copy(from, to, 1000);
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check(rc == 1000, "Normal copy failed: %d", rc);
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check(valid_copy(to, 1000, 'x'), "Normal copy failed.");
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// reset
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memset(to, 'y', 1000);
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// duffs version
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rc = duffs_device(from, to, 1000);
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check(rc == 1000, "Duff's deice failed: %d", rc);
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check(valid_copy(to, 1000, 'x'), "Duff's deice failed copy.");
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// reset
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memset(to, 'y', 1000);
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// my version
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rc = zeds_device(from, to, 1000);
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check(rc == 1000, "Zed's device failed: %d", rc);
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check(valid_copy(to, 1000, 'x'), "Zed's device failed copy.");
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return 0;
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error:
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return 1;
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}
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