Review chapter 05

curs/chap-05-ihs/01-disass/.gitignore

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+/one_var
+/many_vars

curs/chap-05-ihs/01-disass/Makefile

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+CFLAGS = -m32 -fno-PIC -Wall
+LDFLAGS = -m32 -no-pie
+
+.PHONY: all clean
+
+all: one_var many_vars
+
+one_var: one_var.o
+
+one_var.o: one_var.c
+
+many_vars: many_vars.o
+
+many_vars.o: many_vars.c
+
+clean:
+	-rm -f *~
+	-rm -f one_var.o one_var
+	-rm -f many_vars.o many_vars

curs/chap-05-ihs/01-disass/many_vars.c

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+#include <stdio.h>
+#include <string.h>
+
+unsigned int age = 10;
+unsigned short new_age;
+
+struct {
+	unsigned int age;
+	unsigned short occupation;
+	unsigned int new_age;
+	unsigned char location;
+} s;
+
+unsigned int v[4] = {10, 20, 30, 40};
+unsigned int *p;
+
+void g(void)
+{
+	s.age = 10;
+	s.occupation = 20;
+	s.new_age = 30;
+	s.location = 40;
+
+	v[2] = 1000;
+	p = &v[2];
+}
+
+void f(void)
+{
+	new_age = age + 4;
+}
+
+unsigned long long alfa(void)
+{
+	return 119328984948393;
+}
+
+int main(void)
+{
+	return 0;
+}

curs/chap-05-ihs/01-disass/one_var.c

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+#include <stdio.h>
+
+unsigned int age = 32;
+
+void f(void)
+{
+	age = 64;
+}
+
+int main(void)
+{
+	return 0;
+}

curs/chap-05-ihs/02-jmp/.gitignore

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+/je
+/jmp

curs/chap-05-ihs/02-jmp/Makefile

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+CFLAGS = -m32 -fno-PIC -Wall
+LDFLAGS = -m32 -no-pie
+
+.PHONY: all clean
+
+all: jmp je
+
+jmp: jmp.o
+
+jmp.o: jmp.c
+
+je: je.o
+
+je.o: je.c
+
+clean:
+	-rm -f *~
+	-rm -f jmp.o jmp
+	-rm -f je.o je

curs/chap-05-ihs/02-jmp/je.c

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+unsigned int i;
+
+int main(void)
+{
+	i = 0;
+
+	if (i > 0)
+		i += 1;
+	i += 2;
+
+	return 0;
+}

curs/chap-05-ihs/02-jmp/jmp.c

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+unsigned int i;
+
+int main(void)
+{
+	i = 0;
+start:
+	i += 2;
+	goto start;
+	i += 6;
+}

curs/chap-05-ihs/03-flags/.gitignore

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+/flags

curs/chap-05-ihs/03-flags/Makefile

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+NASM = nasm
+AFILES = flags.asm
+OBJS = $(AFILES:.asm=.o)
+ASM_FLAGS = -f elf32 -g -F dwarf
+LD = gcc
+LDFLAGS = -m32 -g -fno-PIC -no-pie
+BINARIES = flags
+
+.PHONY: all clean
+
+all : $(BINARIES)
+
+%.o : %.asm
+	$(NASM) $(ASM_FLAGS) -o $@ $<
+
+%: %.o
+	$(LD) $(LDFLAGS) -o $@ $^
+
+clean:
+	-rm -f *.o $(BINARIES) *.s
+	-rm -f *~

curs/chap-05-ihs/03-flags/flags.asm

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+section .text
+    global main
+
+main:
+    push    ebp
+    mov     ebp, esp
+
+    ; ZF = 1
+    ; cmp eax, eax
+    ; xor eax, eax
+    sub eax, eax
+
+    ; ZF = 0
+    inc eax
+
+    ; CF = 1
+    shr eax, 1
+
+    ; CF = 0
+    shr eax, 1
+
+    ; SF = 1
+    dec eax ; eax <- 0xffffffff
+
+    ; SF = 0
+    inc eax
+
+    ; OF = 1
+
+    ; OF = 0
+
+    ; ZF = 1, CF = 1
+
+    ; ZF = 0, CF = 0
+
+    ; ZF = 0, CF = 1
+
+    ; ZF = 1, CF = 0
+
+    ; SF = 1, OF = 1
+
+    ; SF = 0, OF = 0
+
+    ; SF = 0, OF = 1
+    mov eax, 0x80000000   ; signed int = -2 ^ 31
+    sub eax, 1
+
+    ; SF = 1, OF = 0
+
+    ; SF = 1, ZF = 1
+    ; N/A
+
+    ; SF = 0, ZF = 0
+
+    mov eax, 1
+    ; SF = 0, ZF = 1
+    xor eax, eax
+    ;shr eax, N
+    ;dec eax
+    ;sub eax, 1
+
+    ; SF = 1, ZF = 0
+
+    ; SF = 1, CF = 1
+
+    mov eax, 1
+    ; SF = 0, CF = 0
+    shl eax, 1
+    add eax, 1
+    sub eax, 1
+    xor eax, eax
+
+    ; SF = 0, CF = 1
+
+    ; SF = 1, CF = 0
+
+    pop     ebp
+    ret

curs/chap-05-ihs/04-sum/.gitignore

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+/sum

curs/chap-05-ihs/04-sum/Makefile

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+NASM = nasm
+AFILES = hello_world.asm
+OBJS = $(AFILES:.asm=.o)
+ASM_FLAGS = -f elf32 -g -F dwarf
+LD = gcc
+LDFLAGS = -m32 -g -fno-PIC -no-pie
+BINARIES = sum
+
+.PHONY: all clean
+
+all : $(BINARIES)
+
+%.o : %.asm
+	$(NASM) $(ASM_FLAGS) -o $@ $<
+
+%: %.o
+	$(LD) $(LDFLAGS) -o $@ $^
+
+clean:
+	-rm -f *.o $(BINARIES) *.s
+	-rm -f *~

curs/chap-05-ihs/04-sum/sum.asm

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+%include "../io.mac"
+
+section .bss
+    sum: resd 1
+
+section .text
+    global main
+    extern printf
+
+main:
+        push    ebp
+        mov     ebp, esp
+        mov     eax, 0      ; eax is the loop counter
+        mov     edx, 0      ; edx is sum
+begin:
+        cmp     eax, 100
+        ja      out
+        add     edx, eax
+        add     eax, 1
+        jmp     begin
+out:
+        mov [sum], edx
+
+        PRINTF32 `%d\n\x0`, [sum]
+        nop
+        pop     ebp
+        ret

curs/chap-05-ihs/05-hello-world/README.md

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+# chap-03-demo
+
+1. Demo gdb
+- make
+- gdb hello
+- Comands: b main, r, n
+- set $eax = 0xffffffff
+- set $eip = main
+
+2. Demo gdb
+ step through hello.asm to inspect the changes to the following registers:
+  * EAX, AX, AH, AL
+  * EFLAGS
+  * EIP
+Note: Instructions to whatch are: MOV, ADD, JMP
+
+3. Demo Inspect ~/.gdbinit 
+- less ~/.gdbinit 
+
+cleanup: 
+set disassembly-flavor intel
+set history save on
+
+
+

curs/chap-05-ihs/06-dandamudi/ijump.sasm.asm

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+	;; adaptat cu macrourile SASM - ușor diferite !
+	
+;Sample indirect jump example    IJUMP.ASM
+;
+;        Objective: To demonstrate the use of indirect jump.
+;            Input: Requests a digit character from the user.
+;           Output: Appropriate class selection message.
+%include "io.inc"
+
+section .data
+jump_table  dd  code_for_0   ; indirect jump pointer table
+            dd  code_for_1
+            dd  code_for_2
+            dd  default_code ; default code for digits 3-9
+            dd  default_code
+            dd  default_code
+            dd  default_code
+            dd  default_code
+            dd  default_code
+            dd  default_code
+
+prompt_msg  db  "Type a digit: ",0
+msg_0       db  "Economy class selected.",0
+msg_1       db  "Business class selected.",0
+msg_2       db  "First class selected.",0
+msg_default db  "Not a valid code!",0
+msg_nodigit db  "Not a digit! Try again.",0
+key         db 0
+
+section .text
+global main
+main:
+    mov ebp, esp; for correct debugging         
+read_again:
+        PRINT_STRING   prompt_msg    ; request a digit
+        sub      EAX,EAX       ; EAX = 0
+        GET_CHAR key
+        mov      AL, [key]            ; read input digit and
+        cmp      AL,'0'        ; check to see if it is a digit
+        jb       not_digit
+        cmp      AL,'9'
+        ja       not_digit
+        ; if digit, proceed
+        sub      AL,'0'        ; convert to numeric equivalent
+        mov      ESI,EAX       ; ESI is index into jump table
+        add      ESI,ESI       ; ESI = ESI * 4
+        add      ESI,ESI
+        jmp      [jump_table+ESI] ; indirect jump based on ESI
+test_termination:
+        cmp      AL,2
+        ja       done
+        jmp      read_again 
+code_for_0:
+        PRINT_STRING   msg_0
+        NEWLINE
+        jmp      test_termination
+code_for_1:
+        PRINT_STRING   msg_1
+        NEWLINE
+        jmp      test_termination
+code_for_2:
+        PRINT_STRING   msg_2
+        NEWLINE
+        jmp      test_termination
+default_code:
+        PRINT_STRING   msg_default
+        NEWLINE
+        jmp      test_termination
+
+not_digit:
+        PRINT_STRING   msg_nodigit
+        NEWLINE
+        jmp      read_again
+done:
+	mov 	eax, 1   	
+	mov 	ebx, 0
+	int     0x80		; exit(0)
+        

curs/chap-05-ihs/08-data/.gitignore

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+/data_c
+/data_asm
+/data_c.s