chore: migrate src to solutions

solutions/06_optimization/gpio/Makefile

@@ -0,0 +1,54 @@
+EXE=gpio
+SRCS=$(wildcard *.c)
+
+ifeq ($(target),)
+target=nano
+endif
+
+CFLAGS=-Wall -Wextra -g -c -O1 -MD -std=gnu11 -D_GNU_SOURCE
+
+ifeq ($(target),nano)
+TOOLCHAIN_PATH=/buildroot/output/host/usr/bin/
+TOOLCHAIN=$(TOOLCHAIN_PATH)aarch64-linux-
+CFLAGS+=-mcpu=cortex-a53 -funwind-tables
+##CFLAGS+=-O2 -fno-omit-frame-pointer
+OBJDIR=.obj/nano
+EXEC=$(EXE)
+endif
+
+ifeq ($(target),host)
+EXEC=$(EXE)_h
+endif
+
+CC=$(TOOLCHAIN)gcc
+LD=$(TOOLCHAIN)gcc
+AR=$(TOOLCHAIN)ar
+STRIP=$(TOOLCHAIN)strip
+OBJDUMP=$(TOOLCHAIN)objdump
+
+OBJDIR=.obj/$(target)
+OBJS= $(addprefix $(OBJDIR)/, $(SRCS:.c=.o))
+
+$(OBJDIR)/%o: %c
+	$(CC) $(CFLAGS) $< -o $@
+
+all: $(OBJDIR)/ $(EXEC)
+
+$(EXEC): $(OBJS) $(LINKER_SCRIPT)
+	$(LD) $(OBJS) $(LDFLAGS) -o $@
+
+$(OBJDIR)/:
+	mkdir -p $(OBJDIR)
+
+clean:
+	rm -Rf $(OBJDIR) $(EXEC) $(EXEC)_s *~ t.txt
+
+clean_all: clean
+	rm -Rf .obj $(EXE) $(EXE)_s $(EXE)_a $(EXE)_a_s $(EXE)_h $(EXE)_h_s
+
+dump: all
+	$(OBJDUMP) -dS $(EXEC) > t.txt
+
+-include $(OBJS:.o=.d)
+
+.PHONY: all clean clean_all dump

solutions/06_optimization/gpio/gpio.c

@@ -0,0 +1,87 @@
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#include <time.h>
+#include <sched.h>
+#include <sys/mman.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+#include <stdint.h>
+
+#define GPIO_EXPORT		"/sys/class/gpio/export"
+#define GPIO_UNEXPORT	"/sys/class/gpio/unexport"
+#define GPIO_GPIOG11	"/sys/class/gpio/gpio203"
+#define GPIOG11			"203"
+
+static int open_gpio()
+{
+	// unexport pin out of sysfs (reinitialization)
+	int f = open (GPIO_UNEXPORT, O_WRONLY);
+	write (f, GPIOG11, strlen(GPIOG11));
+	close (f);
+
+	// export pin to sysfs
+	f = open (GPIO_EXPORT, O_WRONLY);
+	write (f, GPIOG11, strlen(GPIOG11));
+	close (f);	
+
+	// config pin
+	f = open (GPIO_GPIOG11 "/direction", O_WRONLY);
+	write (f, "out", 3);
+	close (f);
+
+	// open gpio value attribute
+ 	f = open (GPIO_GPIOG11 "/value", O_RDWR);
+	return f;
+}
+
+/**
+ * main program...
+ */
+int main()
+{
+	cpu_set_t my_set;
+	CPU_ZERO(&my_set);
+	CPU_SET(2, &my_set);
+	sched_setaffinity(0, sizeof(cpu_set_t), &my_set);
+
+	int gpio = open_gpio();
+	bool on = false;
+	struct timespec start_time;
+	struct timespec stop_time;
+	clock_gettime (CLOCK_MONOTONIC, &start_time);  // setup...
+
+
+	// --> measurement with internal timers
+	clock_gettime (CLOCK_MONOTONIC, &start_time);
+	for (int i=0; i<1000; i++) {
+		if (on) {
+			pwrite (gpio, "1", sizeof("1"), 0);
+		} else {
+			pwrite (gpio, "0", sizeof("0"), 0);
+		}
+		on = !on;
+	}
+	clock_gettime (CLOCK_MONOTONIC, &stop_time);
+	long long t = (stop_time.tv_nsec - start_time.tv_nsec) +
+		    (stop_time.tv_sec - start_time.tv_sec) * 1000000000;
+		printf ("pwrite (gpio, \"1\", sizeof(\"1\"), 0) -> %lld ns\n", t/1000);
+
+
+	// --> measurement with oscilloscope
+	while(true) {
+		if (on) {
+			pwrite (gpio, "1", sizeof("1"), 0);
+		} else {
+			pwrite (gpio, "0", sizeof("0"), 0);
+		}
+		on = !on;
+	}
+	
+	return 0;
+}