Examples until p.168

Makefile

@@ -0,0 +1,26 @@
+PROGS = ab a.o b.o ManualNameMangling SimpleSection.o SpecialSymbol \
+		target TinyHelloWorld SectionMapping.elf
+
+all:	$(PROGS)
+
+clean:
+	rm -f $(PROGS)
+
+ab:	a.o b.o
+	$(LD) a.o b.o -e main -o ab
+
+ManualNameMangling: ManualNameMangling.cc
+	$(CXX) ManualNameMangling.cc -o ManualNameMangling
+
+SpecialSymbol: SpecialSymbol.c
+	$(CC) $< -o $@
+
+target: target.c
+	$(CC) -o $@ $< -lbfd
+
+TinyHelloWorld: TinyHelloWorld.c TinyHelloWorld.lds
+	$(CC) -c -fno-builtin TinyHelloWorld.c
+	$(LD) -static -T TinyHelloWorld.lds -o $@ TinyHelloWorld.o 
+
+SectionMapping.elf: SectionMapping.c
+	$(CC) -static $< -o $@

ManualNameMangling.cc

@@ -0,0 +1,12 @@
+#include <stdio.h>
+
+namespace myname {
+	int var = 42;
+}
+
+extern "C" int _ZN6myname3varE;
+
+int main() {
+	printf("%d\n", _ZN6myname3varE);
+	return 0;
+}

SectionMapping.c

@@ -0,0 +1,7 @@
+#include <stdlib.h>
+
+int main() {
+	while(1)
+		sleep(1000);
+	return 0;
+}

SimpleSection.c

@@ -0,0 +1,20 @@
+int printf(const char *format, ...);
+
+int global_init_var = 84;
+int global_uninit_var;
+
+void func1(int i) {
+	printf("%d\n", i);
+}
+
+int main(void) {
+	static int static_var = 85;
+	static int staic_var2;
+
+	int a = 1;
+	int b;
+
+	func1(static_var + staic_var2 + a + b);
+
+	return a;
+}

SpecialSymbol.c

@@ -0,0 +1,14 @@
+#include <stdio.h>
+
+extern char *__executable_start;
+extern char *etext, *_etext, *__etext;
+extern char *edata, *_edata;
+extern char *end, *_end;
+
+int main() {
+	printf("Executable start %X\n", __executable_start);
+	printf("Text end %X %X %X\n", etext, _etext, __etext);
+	printf("Data end %X %X\n", edata, _edata);
+	printf("Executable end %X %X\n", end, _end);
+	return 0;
+}

TinyHelloWorld.c

@@ -0,0 +1,21 @@
+char *str = "Hello World!\n";
+
+void print() {
+	asm("movl $13, %%edx\n\t"	// length
+		"movl %%eax, %%ecx\n\t"	// str
+		"movl $0, %%ebx\n\t"	// STDOUT
+		"movl $4, %%eax\n\t"	// write
+		"int $0x80\n\t"
+		:: "r" (str) : "edx", "ecx", "ebx");
+}
+
+void exit() {
+	asm("movl $42, %ebx\n\t"	// exit code
+		"movl $1, %eax\n\t"	// exit
+		"int $0x80\n\t");
+}
+
+void nomain() {
+	print();
+	exit();
+}

TinyHelloWorld.lds

@@ -0,0 +1,8 @@
+ENTRY(nomain)
+
+SECTIONS
+{
+	. = 0x00400000 + SIZEOF_HEADERS;
+	tinytext : { *(.text) *(.data) *(.rodata) }
+	/DISCARD/ : { *(.comment) }
+}

a.c

@@ -0,0 +1,6 @@
+extern int shared;
+
+int main() {
+	int a = 100;
+	swap(&a, &shared);
+}

b.c

@@ -0,0 +1,5 @@
+int shared = 1;
+
+void swap(int *a, int *b) {
+	*a ^= *b ^= *a ^= *b;
+}

strongWeek.c

@@ -0,0 +1,7 @@
+int weak;
+int strong = 1;
+__attribute__((weak)) weak2 = 2;
+
+int main() {
+	return 0;
+}

target.c

@@ -0,0 +1,9 @@
+#include <stdio.h>
+#include <bfd.h>
+
+int main() {
+	const char **t = bfd_target_list();
+	while(*t) {
+		puts(*t++);
+	}
+}

weakref.c

@@ -0,0 +1,14 @@
+#include <stdio.h>
+#include <pthread.h>
+
+int pthread_create(pthread_t *, const pthread_attr_t *,
+		void *(*) (void *), void *) __attribute__ ((weak));
+
+int main() {
+	if(pthread_create) {
+		puts("This is multi-threaded version.");
+	} else {
+		puts("This is single-threaded version.");
+	}
+	return 0;
+}