--- /dev/null
+#include <stdio.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <string.h>
+#include <stdarg.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#define ARRAY 50
+#define FILEBUF 1024
+
+/* Macro's added by Patrick, mucho neato, aparently ifndef aren't POSIX
+ * anymore */
+#if !defined(MAX)
+#define MAX(A, B) ((A) > (B) ? (A) : (B))
+#endif
+
+#if !defined(MIN)
+#define MIN(A, B) ((A) < (B) ? (A) : (B))
+#endif
+
+/* Macro's added by Jon, allows checking of NULL pointers from memory
+ * allocations without function calls, but how can you return values? */
+#if !defined(MALLOC)
+#define MALLOC(PTR, SIZE) do { PTR = malloc(SIZE); if (PTR == NULL) fatal_sys_error("malloc returned NULL"); } while (0)
+#endif
+
+#if !defined(REALLOC)
+#define REALLOC(PTR, SIZE) do { PTR = realloc(PTR, SIZE); if (PTR == NULL && SIZE != 0) fatal_sys_error("realloc returned NULL"); } while (0)
+#endif
+
+/* Structure for sequences from FASTA files */
+struct fasta {
+ char *id;
+ char *seq;
+ int start;
+ int end;
+ int numres;
+};
+
+void fatal_error (char *message);
+FILE * xfopen (const char *path, const char *mode);
+void * xmalloc (size_t size);
+void * xrealloc (void *ptr, size_t size);
+int diff (char a, char b);
+float pairwise (struct fasta *a, struct fasta *b);
+void populate (struct fasta *a);
+void check_length (struct fasta **array);
+struct fasta ** read_fasta (FILE *fh);
+char ** do_pairwise (struct fasta **array);
+void free_fasta (struct fasta *);
+int jsprintf (char *str, const char *const fmt, ...);
+
+void
+free_fasta (struct fasta *seq) {
+ free(seq->id);
+ free(seq->seq);
+ free(seq);
+}
+
+void
+fatal_error (char *message) {
+ fprintf(stderr, "%s", message);
+ exit(EXIT_FAILURE);
+}
+
+void
+fatal_sys_error (char *message) {
+ perror(message);
+ exit(EXIT_FAILURE);
+}
+
+FILE *
+xfopen (const char *path, const char *mode) {
+ FILE *fh;
+ fh = fopen(path, mode);
+ if (fh == NULL)
+ fatal_sys_error("fopen returned NULL");
+ return fh;
+}
+
+void *
+xmalloc (size_t size) {
+ void *ptr;
+ ptr = (void *) malloc(size);
+ if (ptr == NULL)
+ fatal_sys_error("malloc returned NULL");
+ return ptr;
+}
+
+void *
+xrealloc (void *ptr, size_t size) {
+ ptr = (void *) realloc(ptr, size);
+ if (ptr == NULL && size != 0)
+ fatal_sys_error("realloc returned NULL");
+ return ptr;
+}
+
+/* If the same resdidue return 1 else return 0 */
+int
+diff (char a, char b) {
+ if (a == b && a == '-')
+ return 0;
+ if (a == b)
+ return 1;
+ return 0;
+}
+
+/* Does the pairwise comparison
+ * Compares the regions of the alignment that overlap, common gaps are
+ * ignored, and the number of common residues divided by the length of
+ * the shortest sequence is the identity.
+ * */
+float
+pairwise (struct fasta *a, struct fasta *b) {
+ float result;
+ int start, end, numres, i, id = 0;
+
+ /* If the sequences don't overlap then the seq ID is 0 */
+ if (a->end < b->start || a->start > b->end)
+ return 0;
+
+ start = MIN( a->start, b->start );
+ end = MAX( a->end, b->end );
+ numres = MAX( a->numres, b->numres );
+
+ for (i = start; i < end; i++)
+ id += diff(a->seq[i], b->seq[i]);
+
+ result = 100 * (float) id / (float) numres;
+
+ return result;
+}
+
+/* "Populate" the rest of the fasta structure with information
+ * Gets the start position of the sequence (first non-gap character)
+ * Gets the end position (the last non-gap character)
+ * Gets the number of residues in the sequence (that aren't gaps)
+ * Gaps are represented by '-'
+ * */
+void
+populate (struct fasta *a) {
+ int i;
+ int len = strlen(a->seq);
+
+ a->numres = 0;
+
+ for (i = 0; i <= len; i++) {
+ if (a->seq[i] != '-') {
+ a->start = i;
+ break;
+ }
+ }
+ for (i = len; i > 0; i--) {
+ if (a->seq[i] != '-') {
+ a->end = i;
+ break;
+ }
+ }
+ for (i = a->start; i < a->end; i++) {
+ if (a->seq[i] != '-') {
+ a->numres++;
+ }
+ }
+}
+
+/* Makes sure that all of the sequences are the same length */
+void
+check_length (struct fasta **array) {
+ int i, length;
+
+ if (array[0] != NULL)
+ length = strlen(array[0]->seq);
+ else {
+ fatal_error("check_length() not passed an array of fasta structs\n");
+ }
+
+ for (i = 0; array[i] != NULL; i++) {
+ if (length != (int) strlen(array[i]->seq)) {
+ fatal_error("Not all of the sequences are the same length\n");
+ }
+ }
+}
+
+/* Reads in a FASTA file and returns an array of fasta structures */
+struct fasta **
+read_fasta (FILE *fh) {
+ int i, j, k, c, filesize = 0;
+ char *file;
+ struct fasta **array;
+ struct stat file_stat;
+
+ array = (struct fasta **) malloc(ARRAY * sizeof(struct fasta *));
+
+ /* Find the size of the file and allocate it */
+ fstat(fileno(fh), &file_stat);
+ if (! S_ISREG(file_stat.st_mode)) {
+ fatal_error("Input file is not a regular file");
+ }
+ file = (char *) malloc(sizeof(char) * (file_stat.st_size + 1));
+
+ /* Read in the file and null terminate it */
+ while ((c = getc(fh)) != EOF) {
+ file[filesize++] = c;
+ }
+ file[filesize] = '\0';
+
+ /* Parse the FASTA file into an array of structures */
+ for (i = 0, j = 0, k = 0; i < filesize; i++) {
+
+ /* Begining of FASTA record */
+ if (file[i] == '>') {
+ if (j % ARRAY == 0)
+ array = (struct fasta **) xrealloc(array, sizeof(struct fasta *) * (j + ARRAY));
+
+ /* Initalise the structure */
+ array[j] = (struct fasta *) xmalloc(sizeof(struct fasta));
+ array[j]->id = (char *) xmalloc(sizeof(char));
+ array[j]->seq = (char *) xmalloc(sizeof(char));
+ array[j]->numres = 0;
+
+ /* Read in the ID, terminated by a newline or NULL (end of string) */
+ i++;
+ while (file[i] != '\0' && file[i] != '\n') {
+ if (k % FILEBUF == 0)
+ array[j]->id = (char *) xrealloc(array[j]->id, sizeof(char) * (FILEBUF + k));
+ array[j]->id[k++] = file[i++];
+ }
+ array[j]->id = (char *) xrealloc(array[j]->id, sizeof(char) * k + 1);
+ array[j]->id[k] = '\0';
+ k = 0;
+
+ /* read in the sequence, terminated by a '>' */
+ for (k = 0; file[i] != '\0' && file[i] != '>'; i++) {
+ if (file[i] != '\n') {
+ if (k % FILEBUF == 0)
+ array[j]->seq = (char *) xrealloc(array[j]->seq, sizeof(char) * (FILEBUF + k));
+ array[j]->seq[k++] = file[i];
+ }
+ }
+ array[j]->seq = (char *) xrealloc(array[j]->seq, sizeof(char) * k + 1);
+ array[j]->seq[k] = '\0';
+
+ k = 0;
+ i--;
+ j++;
+ }
+ }
+
+ free(file);
+ array = (struct fasta **) xrealloc(array, sizeof(struct fasta *) * (j + 1));
+ array[j] = NULL;
+
+ /* find the start and end points for the alignments */
+ for (i = 0; array[i] != NULL; i++)
+ populate(array[i]);
+ return array;
+}
+
+char **
+do_pairwise (struct fasta **array) {
+ int j = 0, i = 0, offset = 0, size;
+ char **output;
+
+ /* Find the size of the output and preallocate the space in the output
+ * array */
+ {
+ while (array[i] != NULL)
+ i++;
+
+ /* Number of IDs, each ID, then the upper corner distances, then for
+ * NULL terminator */
+ size = 1 + i + (i * i - i) / 2 + 1;
+
+ output = (char **) xmalloc(sizeof(char *) * size);
+
+ for (i = 0; i < size - 1; i++) {
+ output[i] = (char *) xmalloc(sizeof(char) * FILEBUF);
+ memset(output[i], 0x00, sizeof(char) * FILEBUF);
+ }
+ output[size - 1] = NULL;
+ }
+
+ /* The number of IDs */
+ i = 0;
+ while (array[i] != NULL)
+ i++;
+ jsprintf(output[offset++], "%i", i);
+
+ /* If this statement is above the other one then it core dumps!? */
+
+ /* Each ID */
+ for (i = 0; array[i] != NULL; i++)
+ jsprintf(output[offset++], "%s", array[i]->id);
+
+ /* Upper corner pairwise comparisons */
+ for (i = 0; array[i] != NULL; i++) {
+ for (j = i + 1; array[j] != NULL; j++) {
+ jsprintf(output[offset++], "%f", pairwise(array[i], array[j]));
+ }
+ }
+
+ return output;
+}
+
+/* Grows buffer dynamically to make input fit inside it.
+ * Requires malloc'd pointer to string.
+ * Returns length of string.
+ * */
+int
+jsprintf (char *str, const char *const fmt, ...) {
+ int i, size;
+ va_list ap;
+ va_start(ap, fmt);
+
+ str = (char *) realloc(str, sizeof(char) * FILEBUF);
+
+ for (i = 1; (size = vsnprintf(str, sizeof(char) * FILEBUF * i, fmt, ap)) == -1; i++) {
+ if (i == 100)
+ fatal_error("Reached 100 iterations of vsnprinft, it's probably blown up. Check input");
+ str = (char *) xrealloc(str, sizeof(char) * FILEBUF * i);
+ }
+
+ str = (char *) xrealloc(str, sizeof(char) * size + 1);
+
+ va_end(ap);
+ return size;
+}