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Inline Assembly Juicy Code
Snippets
With a few lines of C...and a few lines of asm... you can
do some great things...
Get CPU Speed
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// Simple set of functions to get your CPU speed, seems
// to work okay on intel processors.
#include
<windows.h> // used for Sleep(..)
#include
<stdio.h> // used for printf(..)
unsigned
__int64 CycleCount()
{
_asm _emit 0x0F
_asm _emit 0x31
}
unsigned
int CpuSpeed()
{
unsigned __int64
start, stop;
unsigned int
total;
start = CycleCount();
Sleep(1000);
stop = CycleCount();
stop = stop - start;
total = (unsigned)(stop/1000000);
return total;
}
void
main()
{
unsigned int
speed = CpuSpeed();
printf("cpu speed: %u", speed);
printf("cpu speed: %u", speed);
printf("cpu speed: %u", speed);
} |
RDTSC __asm _emit 0x0F __asm
_emit 0x31
CPUID __asm _emit 0x0F __asm _emit 0xA2
Simple..Simple String Encription/Decription
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#include
<stdio.h> // printf
#include
<string.h> // strlen
// String Encription/Decription With Assembly
void
encriptstring(char* str,
int key)
{
int len = strlen(str);
for(int i=0;
i<len; i++)
{
int cur=str[i];
__asm
{
mov eax, cur
add eax, key
mov cur, eax
}
str[i] = cur;
}
}
void
decriptstring(char* str,
int key)
{
int len = strlen(str);
for(int i=0;
i<len; i++)
{
int cur=str[i];
__asm
{
mov eax, cur
sub eax, key
mov cur, eax
}
str[i] = cur;
}
}
void
main()
{
char str[] = "secret string";
printf("Original String: %s \n", str);
encriptstring(str, 5);
printf("Encripted String: %s \n", str);
decriptstring(str, 5);
printf("Decripted String: %s \n", str);
} |
View Output:
Original String: secret string
Encripted String: xjhwjy%xywnsl
Decripted String: secret string
Setting Memory To A Fixed Value
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inline
void MemSetWORD(
void *pDest, USHORT data, int iCount)
{
__asm
{
mov edi, pDest ; edi points to our destination in memory
mov ecx, iCount ; number of 16 bit words to write
mov ax, data ; our 16bit data value
rep stosw ; mov data
}
} |
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inline
void MemSetDWORD(
void *pDest, DWORD data, int iCount)
{
__asm
{
mov edi, pDest ; edi points to our destination in memory
mov ecx, iCount ; number of 16 bit words to write
mov eax, data ; our 32-bit data value
rep stosd ; mov data
}
} |
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