os_labs/lab7/switch_case.c

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2020-05-20 13:59:23 +10:00
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#define IS_ALPHA(x) (((x) >= 'A' && (x) <= 'Z') || ((x) >= 'a' && (x) <= 'z'))
typedef union {
uint64_t i64;
char chr[8];
} str_block;
#define CHUNK_SIZE (sizeof(str_block))
int chunk_switch_case(str_block *chunk) {
size_t i = 0;
for (; i < CHUNK_SIZE; ++i) {
if (!chunk->chr[i]) {
break;
}
if (IS_ALPHA(chunk->chr[i])) {
chunk->chr[i] ^= 0x20;
}
}
return i;
}
char *str_switch_case(const char *str) {
size_t str_size = strlen(str);
size_t chunked_read_border = str_size - (str_size%CHUNK_SIZE);
char *result = malloc(str_size);
str_block chunk = {0};
for (size_t i = 0; i < chunked_read_border; i += CHUNK_SIZE) {
memcpy(chunk.chr,str + i, CHUNK_SIZE);
chunk_switch_case(&chunk);
memcpy(result + i, chunk.chr, CHUNK_SIZE);
}
for (size_t i = chunked_read_border; i < str_size; ++i) {
result[i] = str[i];
if (IS_ALPHA(result[i])) {
result[i] ^= 0x20;
}
}
return result;
}
int main(){
str_block chunk = {0};
char stop_reading = 0;
do {
if (isatty(STDIN_FILENO)) {
for (size_t i = 0; i < CHUNK_SIZE; ++i) {
fread(&chunk.chr[i], 1, 1, stdin);
if (chunk.chr[i] == '\n') {
chunk.chr[i] = 0;
break;
}
}
} else {
fread(&chunk.i64, 1, CHUNK_SIZE, stdin);
}
stop_reading = (chunk_switch_case(&chunk) != CHUNK_SIZE);
fwrite(&chunk.chr, 1, CHUNK_SIZE, stdout);
chunk.i64 = 0;
} while (!stop_reading);
return 0;
}