ex2: re-add argc/argv interactivity

exercise2/Makefile

@@ -8,7 +8,7 @@ ARGS    := 1
 NBENCH  := 1
 NPROC   := 3
 
-.PHONY: all clean run
+.PHONY: all clean run parallel
 
 all: clean parallel show
 
@@ -26,7 +26,7 @@ time: $(TARGET)
 
 parallel: $(SRC)
 	mpicc -o $(OUT) $(SRC)
-	cd $(OUTDIR) && mpirun -np $(NPROC) $(TARGET)
+	cd $(OUTDIR) && mpirun -np $(NPROC) $(TARGET) $(ARGS)
 
 show: $(OUTDIR)/mandel.bmp
 	feh $<

exercise2/mandel_mpi.c

@@ -1,5 +1,6 @@
 #include <math.h>
 #include <mpi.h>
+#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -24,6 +25,7 @@ typedef struct {
 } complex_t;
 
 int rank, size;
+bool save = false;
 
 void calculate() {
   for (int i = 0; i < XSIZE; i++) {
@@ -85,6 +87,15 @@ void fancycolour(uchar *p, int iter) {
 }
 
 int main(int argc, char **argv) {
+  if (argc <= 1) {
+    printf("usage: mandel_mpi [y/n]\n");
+    printf("y/n denotes if you want to save the resulting\n");
+    printf("calculations to mandel.bmp or not.\n");
+    return 1;
+  } else {
+    char arg = argv[1][0];
+    save = arg == 'y' || arg == '1';
+  }
   MPI_Init(&argc, &argv);
   MPI_Comm_rank(MPI_COMM_WORLD, &rank);
   MPI_Comm_size(MPI_COMM_WORLD, &size);
@@ -137,8 +148,9 @@ int main(int argc, char **argv) {
 #undef YSIZE
 #define YSIZE 2048
 
-    savebmp("mandel.bmp", total, XSIZE, YSIZE);
-    printf("after save\n");
+    if (save)
+      savebmp("mandel.bmp", total, XSIZE, YSIZE);
+    printf("after save %d\n", save);
   }
 
   MPI_Finalize();