Did a few exersises, most of the way through serial_logger.

combinations/src/combinations.c

@@ -1,30 +1,31 @@
-/* calculates all subsets of the string comb by assigning eatch letter a position in a binary number and counting up. */
+/* calculates all subsets of the string comb by assigning eatch letter a
+ * position in a binary number and counting up. */
 #include <stdio.h>
 #include <string.h>
 
 // #define DEBUG
 
 int main() {
-  char* comb = "ABCD";
+    char *comb = "ABCD";
-  int count = strlen(comb);
+    int count = strlen(comb);
-  // that bitshifting is the same is squaring count
+    // that bitshifting is the same is squaring count
-  int permutations = (1 << count);
+    int permutations = (1 << count);
 
-  printf("string is %s\nthere are %d permutations", comb, permutations);
+    printf("string is %s\nthere are %d permutations", comb, permutations);
 
-  for (unsigned char i = 0; i < permutations; i++) {
+    for (unsigned char i = 0; i < permutations; i++) {
-    for (unsigned char j = 0; j < 4; j++) {
+        for (unsigned char j = 0; j < 4; j++) {
-      // when j=0, will result in 0b0001, when j=1, 0b0010, j=2 0b0100.
+            // when j=0, will result in 0b0001, when j=1, 0b0010, j=2 0b0100.
-      unsigned char mask = 1 << j;
+            unsigned char mask = 1 << j;
 #ifdef DEBUG
-      printf(" j=%x mask=%x, postmask=%x, i=%x", j, mask, (i & mask), i);
+            printf(" j=%x mask=%x, postmask=%x, i=%x", j, mask, (i & mask), i);
 #endif /* ifdef DEBUG */
-      if ((i & mask) != 0) {
+            if ((i & mask) != 0) {
-        printf(" %c", comb[j]);
+                printf(" %c", comb[j]);
-      }
+            }
+        }
+        printf("\n");
     }
-    printf("\n");
-  }
 
-  return 0;
+    return 0;
 }

file_tee/Makefile

@@ -0,0 +1,65 @@
+CC := gcc
+CXX := g++
+OPTIMIZATION := -O3
+CFLAGS = ${OPTIMIZATION} -Wextra -Wall -Wpedantic
+# all: helloworld
+#
+# #automatically built from implicit rules.
+# helloworld: helloworld.c
+#
+# clean:
+# 	rm -f helloworld
+#
+TARGET_EXEC := filetee
+
+BUILD_DIR := ./build
+SRC_DIRS := ./src
+
+# Find all the C and C++ files we want to compile
+# Note the single quotes around the * expressions. The shell will incorrectly expand these otherwise, but we want to send the * directly to the find command.
+SRCS := $(shell find $(SRC_DIRS) -name '*.cpp' -or -name '*.c' -or -name '*.s')
+
+# Prepends BUILD_DIR and appends .o to every src file
+# As an example, ./your_dir/hello.cpp turns into ./build/./your_dir/hello.cpp.o
+OBJS := $(SRCS:%=$(BUILD_DIR)/%.o)
+
+# String substitution (suffix version without %).
+# As an example, ./build/hello.cpp.o turns into ./build/hello.cpp.d
+DEPS := $(OBJS:.o=.d)
+
+# Every folder in ./src will need to be passed to GCC so that it can find header files
+INC_DIRS := $(shell find $(SRC_DIRS) -type d)
+# Add a prefix to INC_DIRS. So moduleA would become -ImoduleA. GCC understands this -I flag
+INC_FLAGS := $(addprefix -I,$(INC_DIRS))
+
+# The -MMD and -MP flags together generate Makefiles for us!
+# These files will have .d instead of .o as the output.
+DEPFLAGS := $(INC_FLAGS) -MMD -MP
+
+# The final build step.
+$(BUILD_DIR)/$(TARGET_EXEC): $(OBJS)
+	$(CXX) $(OBJS) -o $@ $(LDFLAGS)
+
+# Build step for C source
+$(BUILD_DIR)/%.c.o: %.c
+	mkdir -p $(dir $@)
+	$(CC) $(DEPFLAGS) $(CFLAGS) -c $< -o $@
+
+# Build step for C++ source
+$(BUILD_DIR)/%.cpp.o: %.cpp
+	mkdir -p $(dir $@)
+	$(CXX) $(DEPFLAGS) $(CXXFLAGS) -c $< -o $@
+
+
+.PHONY: clean
+clean:
+	rm -r $(BUILD_DIR)
+
+.PHONY: run
+run: $(BUILD_DIR)/$(TARGET_EXEC)
+	$(BUILD_DIR)/$(TARGET_EXEC)
+
+# Include the .d makefiles. The - at the front suppresses the errors of missing
+# Makefiles. Initially, all the .d files will be missing, and we don't want those
+# errors to show up.
+-include $(DEPS)

file_tee/src/file_tee.c

@@ -0,0 +1,69 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+static const char Help[] = "Reads a file and outputs to a file while also printing contents.";
+static const char Usage[] = "INPUT_FILE [OUTPUT_FILE]";
+
+struct arguments {
+	char* inFile;
+	char* outFile;
+};
+
+int main(int argc, char* argv[]) {
+	// for some reason, when doing this with a serial port, log.log never gets written to. I think this is becasue the
+	// program is terminated with ctrl-c, so the file descriptors dont close?.
+
+	struct arguments arguments = {NULL, NULL};
+
+	switch (argc) {
+	case 3:
+		arguments.outFile = argv[2];
+		// fallthrough
+	case 2:
+		arguments.inFile = argv[1];
+		break;
+	default:
+		printf("%s\n%s\n", Usage, Help);
+		return EXIT_FAILURE;
+		break;
+	}
+
+	FILE* inFile = fopen(arguments.inFile, "r");
+	if (!inFile) {
+		printf("error opening file %s\n", arguments.inFile);
+		return EXIT_FAILURE;
+	}
+	FILE* outFile;
+	if (arguments.outFile != NULL) {
+		outFile = fopen(arguments.outFile, "w");
+		if (!outFile) {
+			printf("error opening file %s\n", arguments.outFile);
+			return EXIT_FAILURE;
+		}
+		if (fputs("start of log\n", outFile) < 0) {
+			printf("could not write to %s\n", arguments.outFile);
+			return EXIT_FAILURE;
+		}
+		fflush(outFile);
+	}
+
+	char* lineBuff = NULL;
+	size_t lineBuffSize = 0;
+	ssize_t line_size;
+
+	do {
+		line_size = getline(&lineBuff, &lineBuffSize, inFile);
+		printf("%s", lineBuff);
+		if (arguments.outFile != NULL) {
+			fputs(lineBuff, outFile);
+			fflush(outFile);
+		}
+	} while (line_size >= 0);
+
+	// these things should be done by the OS when we exit.
+	// free(lineBuff);
+	// fclose(inFile);
+	// fclose(outFile);
+
+	return EXIT_SUCCESS;
+}

function_pointer/Makefile

@@ -0,0 +1,65 @@
+CC := gcc
+CXX := g++
+OPTIMIZATION := -O3
+CFLAGS = ${OPTIMIZATION} -Werror -Wextra -Wall -Wpedantic
+# all: helloworld
+#
+# #automatically built from implicit rules.
+# helloworld: helloworld.c
+#
+# clean:
+# 	rm -f helloworld
+#
+TARGET_EXEC := functionpointer
+
+BUILD_DIR := ./build
+SRC_DIRS := ./src
+
+# Find all the C and C++ files we want to compile
+# Note the single quotes around the * expressions. The shell will incorrectly expand these otherwise, but we want to send the * directly to the find command.
+SRCS := $(shell find $(SRC_DIRS) -name '*.cpp' -or -name '*.c' -or -name '*.s')
+
+# Prepends BUILD_DIR and appends .o to every src file
+# As an example, ./your_dir/hello.cpp turns into ./build/./your_dir/hello.cpp.o
+OBJS := $(SRCS:%=$(BUILD_DIR)/%.o)
+
+# String substitution (suffix version without %).
+# As an example, ./build/hello.cpp.o turns into ./build/hello.cpp.d
+DEPS := $(OBJS:.o=.d)
+
+# Every folder in ./src will need to be passed to GCC so that it can find header files
+INC_DIRS := $(shell find $(SRC_DIRS) -type d)
+# Add a prefix to INC_DIRS. So moduleA would become -ImoduleA. GCC understands this -I flag
+INC_FLAGS := $(addprefix -I,$(INC_DIRS))
+
+# The -MMD and -MP flags together generate Makefiles for us!
+# These files will have .d instead of .o as the output.
+DEPFLAGS := $(INC_FLAGS) -MMD -MP
+
+# The final build step.
+$(BUILD_DIR)/$(TARGET_EXEC): $(OBJS)
+	$(CXX) $(OBJS) -o $@ $(LDFLAGS)
+
+# Build step for C source
+$(BUILD_DIR)/%.c.o: %.c
+	mkdir -p $(dir $@)
+	$(CC) $(DEPFLAGS) $(CFLAGS) -c $< -o $@
+
+# Build step for C++ source
+$(BUILD_DIR)/%.cpp.o: %.cpp
+	mkdir -p $(dir $@)
+	$(CXX) $(DEPFLAGS) $(CXXFLAGS) -c $< -o $@
+
+
+.PHONY: clean
+clean:
+	rm -r $(BUILD_DIR)
+
+.PHONY: run
+run: $(BUILD_DIR)/$(TARGET_EXEC)
+	$(BUILD_DIR)/$(TARGET_EXEC)
+
+# Include the .d makefiles. The - at the front suppresses the errors of missing
+# Makefiles. Initially, all the .d files will be missing, and we don't want those
+# errors to show up.
+-include $(DEPS)

function_pointer/src/function_pointer.c

@@ -0,0 +1,26 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+void function0(void) { printf("function 0\n"); }
+void function1(void) { printf("function 1\n"); }
+void function2(void) { printf("function 2\n"); }
+typedef void (*VoidToVoid)(void);
+
+int main(int argc, char *argv[]) {
+    VoidToVoid functions[3] = {function0, function1, function2};
+    if (argc != 2) {
+        printf("one argument only\n");
+        return EXIT_FAILURE;
+    }
+
+    unsigned char index = strtol(argv[1], NULL, 10);
+
+    if (index > 2) {
+        printf("argument must be between 0 and 2\n");
+        return EXIT_FAILURE;
+    }
+
+    functions[index]();
+
+    return EXIT_SUCCESS;
+}

hello_world/src/helloworld.c

@@ -1,8 +1,9 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-int main()
+int main() {
-{
+	if (printf("Hello World\n") < 0) {
-	printf("Hello World\n");
+		return EXIT_FAILURE;
+	}
 	return EXIT_SUCCESS;
 }

retrieve_count/Makefile

@@ -0,0 +1,65 @@
+CC := gcc
+CXX := g++
+OPTIMIZATION := -O3
+CFLAGS = ${OPTIMIZATION} -Werror -Wextra -Wall -Wpedantic
+# all: helloworld
+#
+# #automatically built from implicit rules.
+# helloworld: helloworld.c
+#
+# clean:
+# 	rm -f helloworld
+#
+TARGET_EXEC := retrievecount
+
+BUILD_DIR := ./build
+SRC_DIRS := ./src
+
+# Find all the C and C++ files we want to compile
+# Note the single quotes around the * expressions. The shell will incorrectly expand these otherwise, but we want to send the * directly to the find command.
+SRCS := $(shell find $(SRC_DIRS) -name '*.cpp' -or -name '*.c' -or -name '*.s')
+
+# Prepends BUILD_DIR and appends .o to every src file
+# As an example, ./your_dir/hello.cpp turns into ./build/./your_dir/hello.cpp.o
+OBJS := $(SRCS:%=$(BUILD_DIR)/%.o)
+
+# String substitution (suffix version without %).
+# As an example, ./build/hello.cpp.o turns into ./build/hello.cpp.d
+DEPS := $(OBJS:.o=.d)
+
+# Every folder in ./src will need to be passed to GCC so that it can find header files
+INC_DIRS := $(shell find $(SRC_DIRS) -type d)
+# Add a prefix to INC_DIRS. So moduleA would become -ImoduleA. GCC understands this -I flag
+INC_FLAGS := $(addprefix -I,$(INC_DIRS))
+
+# The -MMD and -MP flags together generate Makefiles for us!
+# These files will have .d instead of .o as the output.
+DEPFLAGS := $(INC_FLAGS) -MMD -MP
+
+# The final build step.
+$(BUILD_DIR)/$(TARGET_EXEC): $(OBJS)
+	$(CXX) $(OBJS) -o $@ $(LDFLAGS)
+
+# Build step for C source
+$(BUILD_DIR)/%.c.o: %.c
+	mkdir -p $(dir $@)
+	$(CC) $(DEPFLAGS) $(CFLAGS) -c $< -o $@
+
+# Build step for C++ source
+$(BUILD_DIR)/%.cpp.o: %.cpp
+	mkdir -p $(dir $@)
+	$(CXX) $(DEPFLAGS) $(CXXFLAGS) -c $< -o $@
+
+
+.PHONY: clean
+clean:
+	rm -r $(BUILD_DIR)
+
+.PHONY: run
+run: $(BUILD_DIR)/$(TARGET_EXEC)
+	$(BUILD_DIR)/$(TARGET_EXEC)
+
+# Include the .d makefiles. The - at the front suppresses the errors of missing
+# Makefiles. Initially, all the .d files will be missing, and we don't want those
+# errors to show up.
+-include $(DEPS)

retrieve_count/src/retrieve_count.c

@@ -0,0 +1,19 @@
+#include <stdio.h>
+
+static unsigned int counter = 0;
+
+void increment(void) {
+    // static unsigned int counter = 0;
+    counter++;
+    // printf("%d ", counter);
+}
+
+int retrieve(void) { return counter; }
+
+int main(void) {
+    for (int i = 0; i < 5; i++) {
+        increment();
+        printf("%d ", retrieve());
+    }
+    return 0;
+}