Split more ia-32/main

Author: cirosantilli

README.md

@@ -13,13 +13,13 @@ x86 only for now, but we'd love to try out other architectures.
     1. [Assemblers](assemblers.md)
     1. [Pros and cons](pros-and-cons.md)
     1. [Intel processor history](intel-processor-history.md)
+    1. [CPU Architecture](cpu-architecture.md)
 1.  [IA-32](ia-32.md)
     1. [IA-32 code](ia-32/)
     1. [Segmentation](segmentation.md)
         1. [Rings](rings.md)
 1.  [x86-64](x86-64/)
 1.  [Calling conventions](calling-conventions.md)
-    1. [cdecl](cdecl.md)
 1.  [Containers](containers.md)
     1.  [ELF](elf.md)
         1. [ELF hello world](elf-hello-world.md)

bibliography.md

@@ -56,5 +56,13 @@
 
     Washington university course that covers branch prediction, cache and other CPU internals
 
+## Libraries
+
+-   <https://github.com/aquynh/capstone>
+
+    Looks like the best free disassembly library out there.
+
+    Binutils cannot be used as a library to disassemble? Sad.
+
 [Itanium C++ ABI]: http://mentorembedded.github.io/cxx-abi/abi.html
 [System V ABI AMD64]: http://www.x86-64.org/documentation_folder/abi-0.99.pdf

binutils.md

@@ -12,6 +12,7 @@ Also contains GDB.
 
 ## Makefile
 
+    sudo apt-get build-dep gdb
     mkdir binutils-gdb
     cd binutils-gdb
     git clone git://sourceware.org/git/binutils-gdb.git src
@@ -49,7 +50,6 @@ Try it out on Linux:
     ./ld -o main.out main.o
     ./main.out
 
-
 Took 3 minutes in a 2013 computer.
 
 Why `--with-sysroot` is needed <https://sourceware.org/ml/binutils/2007-02/msg00274.html>. Why not make it the default?!

calling-conventions.md

@@ -16,11 +16,9 @@ GCC allows to specify calling convention explicitly as:
 
 where `cdecl` is the name of the calling convention.
 
-In IA32, [cdecl](cdecl.md) is the most popular in Linux, and stdcall the most popular in Windows, but there exist many others.
+In IA32, cdecl is the most popular in Linux, and stdcall the most popular in Windows, but there exist many others.
 
-## Call C function form assembly
-
-TODO link to example code.
+## Call C function from assembly
 
 To call a C function from assembly you need to:
 
@@ -33,17 +31,3 @@ To call a C function from assembly you need to:
     For example, `exit` may be called `_exit` on certain compilers such as GCC elf format.
 
     This is not specified by ANSI C, so the only portable alternative is via macros.
-
--   declare the function you want to call as extern.
-
-    NASM for example has the `extern` directive.
-
--   compile into an object file and then compile that object file with the C object files.
-
-    For example with nasm:
-
-        nasm -o a.o a.asm
-        gcc -c c.c -o c.o
-        gcc -o main a.o c.o
-
-    You can also call stdlib functions if you want, since GCC links to them for you.

compiler-generated/README.md

@@ -6,7 +6,8 @@ Let's see what our compilers are compiling to.
     1. [GCC](gcc.md)
 1.  C
     1.  [hello_world.c](hello_world.c)
-    1.  [function_int_int_int.c](function_int_int_int.c)
+    1.  Functions
+        1.  [function_int_int_int.c](function_int_int_int.c)
     1.  [return_struct.c](return_struct.c)
     1.  switch
         1.  [switch3.c](switch3.c)

compiler-generated/function_call_another.c

@@ -0,0 +1,31 @@
+/*
+A function that calls another.
+*/
+
+#include <stdio.h>
+#include <time.h>
+
+int func1(int i, int j, int k) {
+    int l;
+    l = i + j + k;
+    return l;
+}
+
+/*
+This function calls another function.
+
+In rsp must be moved to:
+
+- store all arguments and local variables.
+- align to 0x10 in x86-64
+*/
+int func0(int i, int j, int k) {
+    int l;
+    l = func1(i, j, k);
+    return l;
+}
+
+int main() {
+    printf("%d\n", func0(1, 2, 3));
+    return 0;
+}

compiler-generated/function_int_int_int.c

@@ -1,11 +1,18 @@
-/* Simple function that takes two ints and returns a third. */
+/*
+Simple function that takes two ints and returns a third.
+*/
 
 #include <stdio.h>
 
 /*
 GCC 4.8 -O3 reduces this to a single lea.
+
+At `-O0`, when there is no function call inside this function, `rsp` is not changed.
+Such function is called a leaf function.
+
+TODO why does the first variable go to `rbp - 0x14` instead of `rbp - 0x4`?
 */
-int my_function(int i, int j) {
+int func0(int i, int j) {
     int k;
     k = i + j;
     return k;
@@ -15,6 +22,6 @@ int main() {
     /*
     GCC 4.8 -O3 resolves the function call into a constant.
     */
-    printf("%d\n", my_function(1, 2));
+    printf("%d\n", func0(1, 2));
     return 0;
 }

compiler-generated/gcc/builtin_expect.c

@@ -5,7 +5,6 @@ int main() {
     int i;
     i = !time(NULL);
     if (__builtin_expect(i, 0))
-        printf("%d\n", i);
-    puts("a");
+        puts("a");
     return 0;
 }

compiler-generated/gcc/builtin_expect_off.c

@@ -5,7 +5,6 @@ int main() {
     int i;
     i = !time(NULL);
     if (i)
-        printf("%d\n", i);
-    puts("a");
+        puts("a");
     return 0;
 }

cpu-architecture.md

@@ -0,0 +1,3 @@
+# CPU Architecture
+
+<https://en.wikipedia.org/wiki/Accumulator_%28computing%29>: same as general purpose registers, but specially in the past or current microcontrollers where there was a single GP register!