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Home > Forums > Programmers > Languages > Assembly Forum

ASM typecasting

CODE

crc32_out := CRC32tab[Byte(crc32_out xor DWord(PChar(inbuffer)^))] xor
((crc32_out shr 8) and $00ffffff);

In converting this Pascal code, the thing I struggled with was the typecasting parts.  Now I'm fine with the DWord typecast for most part ( XOR E?X, E?X then move byte to ?L ).

Now the Byte typecast was a little bit more trouble because I needed the lower byte of that result ( ?L ) to address the array represented by CRC32tab.  I figured it out by using 3 or 4 instructions to clear the high 24-bits of the extended register.

But the question is this: Is there a better way to approach this problem?

It is not possible for anyone to acknowledge truth when their salary depends on them not doing it.

Glenn9999 (Programmer)

1 Feb 11 23:52

But the question is this: Is there a better way to approach this problem?

Got this answered. Needed the MOVZX instruction.

It is not possible for anyone to acknowledge truth when their salary depends on them not doing it.

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