add backwards tests

factorial and loop have 8, respectively 9, bytes of instructions before the
jump backwards. Maybe I'll have to redo them, in the worst case I have to do
useless functions

hook_tests/backwards.asm

+format ms64 coff
+
+section '.text' code readable  executable
+
+use64
+
+public _loop
+_loop:
+	xor eax, eax
+	inc eax
+	mov rbx, rdx ; RDX is overwritten by mul
+@again:
+	cmp rbx, 0
+	je @loop_end
+	mul rcx
+	dec rbx
+	jmp @again
+@loop_end:
+	ret
+
+public _tail_recursion
+_tail_recursion:
+	test ecx, ecx
+	je @is_0
+	mov eax, ecx
+	dec ecx
+@loop:
+	test ecx, ecx
+	jz @tr_end
+
+	mul ecx
+	dec ecx
+	
+	jnz @loop
+	jmp @tr_end
+@is_0:
+	mov eax, 1
+@tr_end:
+	ret

hook_tests/backwards.h

+#pragma once
+extern "C" {
+	/**
+	* Raises @num @cnt times
+	*
+	* @param num
+	* @param cnt
+	*/
+	uint32_t _loop(uint32_t num, uint32_t cnt);
+
+	/**
+	* Computes factorial
+	*
+	* @param x
+	*/
+	uint32_t _tail_recursion(uint32_t x);
+}

hook_tests/hook_tests.vcxproj

   </ItemDefinitionGroup>
   <ItemGroup>
     <ClInclude Include="advanced_instructions.h" />
+    <ClInclude Include="backwards.h" />
     <ClInclude Include="catch.hpp" />
     <ClInclude Include="simple_tests.h" />
   </ItemGroup>
   </ItemGroup>
   <ItemGroup>
     <None Include="advanced_instructions.asm" />
+    <None Include="backwards.asm" />
     <None Include="README.md" />
     <None Include="simple_tests.asm" />
   </ItemGroup>
   <ItemGroup>
     <Object Include="advanced_instructions.obj" />
+    <Object Include="backwards.obj" />
     <Object Include="simple_tests.obj" />
   </ItemGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />

hook_tests/hook_tests.vcxproj.filters

     <ClInclude Include="advanced_instructions.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="backwards.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="main.cpp">
     <None Include="advanced_instructions.asm">
       <Filter>Source Files</Filter>
     </None>
+    <None Include="backwards.asm">
+      <Filter>Source Files</Filter>
+    </None>
   </ItemGroup>
   <ItemGroup>
     <Object Include="simple_tests.obj" />
     <Object Include="advanced_instructions.obj" />
+    <Object Include="backwards.obj" />
   </ItemGroup>
 </Project>

hook_tests/main.cpp

 #include "catch.hpp"
 #include "simple_tests.h"
 #include "advanced_instructions.h"
+#include "backwards.h"
 
 TEST_CASE("Simple functions work as expected, unhooked") {
 	REQUIRE(_small() == 0);
 	REQUIRE((result[1] - result[2]) < DBL_EPSILON);
 	REQUIRE((result[2] - result[3]) < DBL_EPSILON);
 	REQUIRE((result[0] - 3.) < DBL_EPSILON);
+}
+
+TEST_CASE("Loops & tail recursion work as expected, unhook") {
+	REQUIRE(_loop(2, 3) == 8);
+	REQUIRE(_loop(5, 3) == 125);
+	REQUIRE(_loop(5, 0) == 1);
+	REQUIRE(_loop(5, 1) == 5);
+
+	REQUIRE(_tail_recursion(0) == 1);
+	REQUIRE(_tail_recursion(1) == 1);
+	REQUIRE(_tail_recursion(2) == 2);
+	REQUIRE(_tail_recursion(5) == 120);
 }