February 14, 2007 Helping getting dos tickcount | ||||
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Hi, I love DMC and am (slowly) getting used to doing some programming in ASM as well. I am trying to figure out that processor speed by using rdtsc and then keeping a counter outside of that. The problem I run into is that for some reason I can't correctly get the BIOS tick count on two separate Intel machines. I have tried a crap load of different ways to reference the same memory. Here is the code and the output is the same number over and over no matter how many times I run the program. Your help getting my head "out" would be much appreciated. BTW, I took this example code from the Intel CPU identification and CPUID instruction document. static unsigned int SEG_BIOS_DATA_AREA = 0x040; static unsigned int OFFSET_TICK_COUNT = 0x06c; unsigned int testVal; asm { push SEG_BIOS_DATA_AREA pop es mov esi, OFFSET_TICK_COUNT // The BIOS tick count updates mov ebx, DWORD PTR es:[esi] // ~ 18.2 times per second. mov testVal,ebx } printf("Time Value:%u",testVal); |
February 16, 2007 Re: Helping getting dos tickcount | ||||
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Posted in reply to Arthur Becker | Hello, Arthur Becker schrieb... > I love DMC and am (slowly) getting used to doing some programming in ASM as > well. I am trying to figure out that processor speed by using rdtsc and then > keeping a counter outside of that. > The problem I run into is that for some reason I can't correctly get the BIOS > tick count on two separate Intel machines. I have tried a crap load of > different ways to reference the same memory. > Here is the code and the output is the same number over and over no matter how > many times I run the program. Your help getting my head "out" would be much > appreciated. BTW, I took this example code from the Intel CPU identification > and CPUID instruction document. > > static unsigned int SEG_BIOS_DATA_AREA = 0x040; > static unsigned int OFFSET_TICK_COUNT = 0x06c; > unsigned int testVal; > asm > { > push SEG_BIOS_DATA_AREA > pop es > mov esi, OFFSET_TICK_COUNT > // The BIOS tick count updates > mov ebx, DWORD PTR es:[esi] > // ~ 18.2 times per second. > mov testVal,ebx > } > printf("Time Value:%u",testVal); Which memory model do you use? This example will not work with the DOS extented (Option -mx) or as a Windows application. If you compile this example with dmc -ms t.c you will get the ticker: /**************** t.c ***********************/ #include <stdio.h> unsigned int GetBiosTicker() { unsigned int btick; asm { mov ax,0x0040 mov es,ax mov si,0x006c mov ax,es:[si] mov btick,ax } return btick; }//GetBiosTicker int main() { printf("Bios-Tick = %u\n", GetBiosTicker()); return 0; } /**************** end t.c ***********************/ - Heinz |
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