Zeichnungen: Pull-Up- und Pull-Down-Widerstände 14.1.2021

Beispiel-Programme 21.1.2021

20210121/alignment-1.c

+#include <stdio.h>
+#include <stdint.h>
+
+int main (void)
+{
+  uint8_t a = 42;
+  uint16_t b = 1117;
+  uint8_t c = 23;
+  printf ("a = %d, b = %d, c = %d\n", a, b, c);
+}

20210121/alignment-2.c

+#include <stdio.h>
+#include <stdint.h>
+
+int main (void)
+{
+  uint8_t a = 42;
+  uint16_t b = 1117;
+  uint8_t c = 23;
+  printf ("a = %d, b = %d, c = %d\n", a, b, c);
+  a = 0;
+  b = 0;
+  c = 0;
+  printf ("a = %d, b = %d, c = %d\n", a, b, c);
+}

20210121/alignment-3.c

+#include <stdio.h>
+#include <stdint.h>
+
+int main (void)
+{
+  uint8_t a = 42;
+  uint16_t b = 1117;
+  uint8_t c = 23;
+  printf ("a = %d, b = %d, c = %d\n", a, b, c);
+  uint32_t *p = &a;
+  *p = 0;
+  printf ("a = %d, b = %d, c = %d\n", a, b, c);
+}

20210121/alignment-4.c

+#include <stdio.h>
+#include <stdint.h>
+
+int main (void)
+{
+  uint8_t a = 42;
+  uint16_t b = 1117;
+  uint8_t c = 23;
+  printf ("a = %d, b = %d, c = %d\n", a, b, c);
+  uint32_t *p = (uint32_t *) &a;
+  *p = 0;
+  printf ("a = %d, b = %d, c = %d\n", a, b, c);
+}

20210121/alignment-5-32.s

+	.file	"alignment-5.c"
+	.text
+	.section	.rodata
+.LC0:
+	.string	"a = %d, b = %d, c = %d\n"
+	.text
+	.globl	main
+	.type	main, @function
+main:
+.LFB0:
+	.cfi_startproc
+	leal	4(%esp), %ecx
+	.cfi_def_cfa 1, 0
+	andl	$-16, %esp
+	pushl	-4(%ecx)
+	pushl	%ebp
+	.cfi_escape 0x10,0x5,0x2,0x75,0
+	movl	%esp, %ebp
+	pushl	%ebx
+	pushl	%ecx
+	.cfi_escape 0xf,0x3,0x75,0x78,0x6
+	.cfi_escape 0x10,0x3,0x2,0x75,0x7c
+	subl	$16, %esp
+	call	__x86.get_pc_thunk.bx
+	addl	$_GLOBAL_OFFSET_TABLE_, %ebx
+	movb	$42, -17(%ebp)                        # #include <stdio.h>
+	movw	$1117, -10(%ebp)                      # #include <stdint.h>
+	movb	$23, -11(%ebp)                        #
+	movzbl	-11(%ebp), %ecx                       # int main (void)
+	movzwl	-10(%ebp), %edx                       # {
+	movzbl	-17(%ebp), %eax                       #   uint8_t a = 42;
+	movzbl	%al, %eax                             #   uint16_t b = 1117;
+	pushl	%ecx                                  #   uint8_t c = 23;
+	pushl	%edx                                  #   printf ("a = %d, b = %d, c = %d\n", a, b, c);
+	pushl	%eax                                  #   uint64_t *p = (uint64_t *) &a;
+	leal	.LC0@GOTOFF(%ebx), %eax               #   *p = 0;
+	pushl	%eax                                  #   printf ("a = %d, b = %d, c = %d\n", a, b, c);
+	call	printf@PLT                            # }
+	addl	$16, %esp
+	leal	-17(%ebp), %eax
+	movl	%eax, -16(%ebp)
+	movl	-16(%ebp), %eax
+	movl	$0, (%eax)
+	movl	$0, 4(%eax)                           #  -9 \ b
+	movzbl	-11(%ebp), %ecx                       # -10 /      -.
+	movzwl	-10(%ebp), %edx                       # -11 - c     |
+	movzbl	-17(%ebp), %eax                       # -12         |
+	movzbl	%al, %eax                             # -13          } auf 0 gesetzt
+	pushl	%ecx                                  # -14         |
+	pushl	%edx                                  # -15         |
+	pushl	%eax                                  # -16         |
+	leal	.LC0@GOTOFF(%ebx), %eax               # -17 - a    -'
+	pushl	%eax
+	call	printf@PLT
+	addl	$16, %esp
+	movl	$0, %eax
+	leal	-8(%ebp), %esp
+	popl	%ecx
+	.cfi_restore 1
+	.cfi_def_cfa 1, 0
+	popl	%ebx
+	.cfi_restore 3
+	popl	%ebp
+	.cfi_restore 5
+	leal	-4(%ecx), %esp
+	.cfi_def_cfa 4, 4
+	ret
+	.cfi_endproc
+.LFE0:
+	.size	main, .-main
+	.section	.text.__x86.get_pc_thunk.bx,"axG",@progbits,__x86.get_pc_thunk.bx,comdat
+	.globl	__x86.get_pc_thunk.bx
+	.hidden	__x86.get_pc_thunk.bx
+	.type	__x86.get_pc_thunk.bx, @function
+__x86.get_pc_thunk.bx:
+.LFB1:
+	.cfi_startproc
+	movl	(%esp), %ebx
+	ret
+	.cfi_endproc
+.LFE1:
+	.ident	"GCC: (Debian 8.3.0-6) 8.3.0"
+	.section	.note.GNU-stack,"",@progbits

20210121/alignment-5.c

+#include <stdio.h>
+#include <stdint.h>
+
+int main (void)
+{
+  uint8_t a = 42;
+  uint16_t b = 1117;
+  uint8_t c = 23;
+  printf ("a = %d, b = %d, c = %d\n", a, b, c);
+  uint64_t *p = (uint64_t *) &a;
+  *p = 0;
+  printf ("a = %d, b = %d, c = %d\n", a, b, c);
+}

20210121/answer-32.s

+	.file	"answer.c"
+	.text
+	.section	.rodata.str1.1,"aMS",@progbits,1
+.LC0:
+	.string	"%d\n"
+	.text
+	.globl	main
+	.type	main, @function
+main:
+.LFB11:
+	.cfi_startproc
+	leal	4(%esp), %ecx
+	.cfi_def_cfa 1, 0
+	andl	$-16, %esp
+	pushl	-4(%ecx)
+	pushl	%ebp
+	.cfi_escape 0x10,0x5,0x2,0x75,0                   # #include <stdio.h>
+	movl	%esp, %ebp                                #
+	pushl	%ebx                                      # int answer = 23;
+	pushl	%ecx                                      #
+	.cfi_escape 0xf,0x3,0x75,0x78,0x6                 # int main (void)
+	.cfi_escape 0x10,0x3,0x2,0x75,0x7c                # {
+	call	__x86.get_pc_thunk.bx                     #   answer += 19;
+	addl	$_GLOBAL_OFFSET_TABLE_, %ebx              #   printf ("%d\n", answer);
+	movl	answer@GOTOFF(%ebx), %eax                 #   return 0;
+	addl	$19, %eax                                 # }
+	movl	%eax, answer@GOTOFF(%ebx)
+	subl	$8, %esp
+	pushl	%eax
+	leal	.LC0@GOTOFF(%ebx), %eax
+	pushl	%eax
+	call	printf@PLT
+	addl	$16, %esp
+	movl	$0, %eax
+	leal	-8(%ebp), %esp
+	popl	%ecx
+	.cfi_restore 1
+	.cfi_def_cfa 1, 0
+	popl	%ebx
+	.cfi_restore 3
+	popl	%ebp
+	.cfi_restore 5
+	leal	-4(%ecx), %esp
+	.cfi_def_cfa 4, 4
+	ret
+	.cfi_endproc
+.LFE11:
+	.size	main, .-main
+	.globl	answer
+	.data
+	.align 4
+	.type	answer, @object
+	.size	answer, 4
+answer:
+	.long	23
+	.section	.text.__x86.get_pc_thunk.bx,"axG",@progbits,__x86.get_pc_thunk.bx,comdat
+	.globl	__x86.get_pc_thunk.bx
+	.hidden	__x86.get_pc_thunk.bx
+	.type	__x86.get_pc_thunk.bx, @function
+__x86.get_pc_thunk.bx:
+.LFB12:
+	.cfi_startproc
+	movl	(%esp), %ebx
+	ret
+	.cfi_endproc
+.LFE12:
+	.ident	"GCC: (Debian 8.3.0-6) 8.3.0"
+	.section	.note.GNU-stack,"",@progbits

20210121/answer.c

+#include <stdio.h>
+
+int answer = 23;
+
+int main (void)
+{
+  answer += 19;
+  printf ("%d\n", answer);
+  return 0;
+}

20210121/answer.disassemble

+(gdb) disassemble /r main
+Dump of assembler code for function main:
+   0x0000000000001135 <+0>:     48 83 ec 08             sub    $0x8,%rsp
+   0x0000000000001139 <+4>:     8b 05 f1 2e 00 00       mov    0x2ef1(%rip),%eax        # 0x4030 <answer>
+   0x000000000000113f <+10>:    8d 70 13                lea    0x13(%rax),%esi
+   0x0000000000001142 <+13>:    89 35 e8 2e 00 00       mov    %esi,0x2ee8(%rip)        # 0x4030 <answer>
+   0x0000000000001148 <+19>:    48 8d 3d b5 0e 00 00    lea    0xeb5(%rip),%rdi         # 0x2004
+   0x000000000000114f <+26>:    b8 00 00 00 00          mov    $0x0,%eax
+   0x0000000000001154 <+31>:    e8 d7 fe ff ff          callq  0x1030 <printf@plt>
+   0x0000000000001159 <+36>:    b8 00 00 00 00          mov    $0x0,%eax
+   0x000000000000115e <+41>:    48 83 c4 08             add    $0x8,%rsp
+   0x0000000000001162 <+45>:    c3                      retq
+End of assembler dump.
+
+                                ^^^^^^^^^^^^^^^^^^^^    ^^^^^^^^^^^^^^^^^^^^^^^^^^
+                                Maschinensprache        Assembler

20210121/answer.s

+	.file	"answer.c"
+	.text
+	.section	.rodata.str1.1,"aMS",@progbits,1
+.LC0:
+	.string	"%d\n"
+	.text
+	.globl	main
+	.type	main, @function
+main:
+.LFB11:
+	.cfi_startproc
+	subq	$8, %rsp
+	.cfi_def_cfa_offset 16                #  #include <stdio.h>
+	movl	answer(%rip), %eax            #
+	leal	19(%rax), %esi                #  int answer = 23;
+	movl	%esi, answer(%rip)            #
+	leaq	.LC0(%rip), %rdi              #  int main (void)
+	movl	$0, %eax                      #  {
+	call	printf@PLT                    #    answer += 19;
+	movl	$0, %eax                      #    printf ("%d\n", answer);
+	addq	$8, %rsp                      #    return 0;
+	.cfi_def_cfa_offset 8                 #  }
+	ret
+	.cfi_endproc
+.LFE11:
+	.size	main, .-main
+	.globl	answer
+	.data
+	.align 4
+	.type	answer, @object
+	.size	answer, 4
+answer:
+	.long	23
+	.ident	"GCC: (Debian 8.3.0-6) 8.3.0"
+	.section	.note.GNU-stack,"",@progbits