Add basic parallel implementation

main.c

@@ -2,24 +2,159 @@
 #include <string.h>
 #include "kmp.h"
 #include "util.h"
+#include <mpi.h>
+#include <malloc.h>
 
+#define MASTER 0
+#define DEFAULT_TAG 17
+
+char *read_text();
+
+char *read_pattern();
+
+void find_end(int, char *, char *, int **, int *);
+
+void apply_shift(int, int *, int);
+
+int sum_array(int *, int);
 
 int main() {
-    char *patter = "acabacacd";
-    char *text = "acfacabacabacacdac";
+    int rank, size, private_text_len, text_len, pattern_len;
+    char *pattern, *text;
 
-    int pattern_len = strlen(patter);
+    MPI_Init(NULL, NULL);
+
+    MPI_Comm_size(MPI_COMM_WORLD, &size);
+    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+
+    if (rank == MASTER) {
+        text = read_text();
+        pattern = read_pattern();
+        printf("text: %s\n", text);
+        printf("pattern: %s\n", pattern);
+        text_len = strlen(text);
+        pattern_len = strlen(pattern);
+        private_text_len = text_len / size; // TODO: size non divisibile
+    }
+
+    MPI_Bcast(&private_text_len, 1, MPI_INT, MASTER, MPI_COMM_WORLD);
+
+    char *private_text = (char *) malloc(sizeof(char) * (private_text_len + 1));
+
+    MPI_Scatter(text, private_text_len, MPI_CHAR, private_text, private_text_len, MPI_CHAR, MASTER, MPI_COMM_WORLD);
+    private_text[private_text_len] = '\0';
+
+    printf("%d -> input: %s\n", rank, private_text);
+
+    MPI_Bcast(&pattern_len, 1, MPI_INT, MASTER, MPI_COMM_WORLD);
+
+    if (rank != MASTER) {
+        pattern = (char *) malloc(sizeof(char) * (pattern_len + 1));
+    }
+
+    MPI_Bcast(pattern, pattern_len + 1, MPI_CHAR, MASTER, MPI_COMM_WORLD);
 
-    // long proper suffix array
     int lps[pattern_len];
 
-    create_lps(patter, pattern_len, lps);
+    create_lps(pattern, pattern_len, lps);
 
-    int match_number = 0;
-    int residue;
+    int match_number = 0, residue;
+    int *matches = search_pattern(private_text, pattern, lps, &match_number, &residue);
 
-    int *matches = search_pattern(text, patter, lps, &match_number, &residue);
 
+    if (rank + 1 != size) {
+        MPI_Send(&residue, 1, MPI_INT, rank + 1, DEFAULT_TAG, MPI_COMM_WORLD);
+    }
+
+    if (rank != 0) {
+        MPI_Recv(&residue, 1, MPI_INT, rank - 1, DEFAULT_TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
+        if (residue != 0)
+            find_end(residue, pattern, private_text, &matches, &match_number);
+    }
+
+    int shift = rank * private_text_len;
+    apply_shift(shift, matches, match_number);
+
+    printf("%d -> result number: %d\n", rank, match_number);
+
+    if (rank == MASTER) {
+        int match_numbers[size];
+        match_numbers[MASTER] = match_number;
+
+        for (int i = 0; i < size; ++i) {
+            if (i == MASTER) continue;
+
+            MPI_Recv(match_numbers + i, 1, MPI_INT, i, DEFAULT_TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
+        }
+
+        match_number = sum_array(match_numbers, size);
+        matches = (int *) realloc(matches, sizeof(int) * match_number);
+
+        int offset = 0;
+        for (int i = 0; i < size; ++i) {
+            if (i == MASTER) {
+                offset += match_numbers[i];
+                continue;
+            }
+
+            MPI_Recv(matches + offset, match_numbers[i], MPI_INT, i, DEFAULT_TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
+            offset += match_numbers[i];
+        }
+    } else {
+        MPI_Send(&match_number, 1, MPI_INT, MASTER, DEFAULT_TAG, MPI_COMM_WORLD);
+        MPI_Send(matches, match_number, MPI_INT, MASTER, DEFAULT_TAG, MPI_COMM_WORLD);
+    }
+
+    MPI_Finalize();
+
+    if (rank == MASTER) {
+        printf("total matches: %d\n", match_number);
+        printf("matches index: ");
         print_array(matches, match_number);
-    printf("%d\n", residue);
+    }
+}
+
+char *read_text() {
+    // TODO
+    return "abc";
+}
+
+char *read_pattern() {
+    // TODO
+    return "mamma";
+}
+
+void find_end(int residue, char *pattern, char *text, int **matches, int *match_number) {
+    int pattern_index = residue;
+    int text_index = 0;
+    int text_len = strlen(text);
+    int pattern_len = strlen(pattern);
+
+    if (pattern_len - residue > text_len) return;
+
+    while (pattern_index < pattern_len && pattern[pattern_index] == text[text_index]) {
+        pattern_index++;
+        text_index++;
+    }
+
+    if (pattern_index != pattern_len) return;
+
+    *match_number = *match_number + 1;
+    *matches = (int *) realloc(*matches, *match_number * sizeof(int));
+    (*matches)[*match_number - 1] = -residue;
+}
+
+void apply_shift(int shift, int *array, int size) {
+    for (int i = 0; i < size; ++i) {
+        array[i] += shift;
+    }
+}
+
+int sum_array(int *array, int size) {
+    int sum = 0;
+    for (int i = 0; i < size; ++i) {
+        sum += array[i];
+    }
+
+    return sum;
 }