On 02:28 Sat 13 Sep , Sri Ram K Vemulpali wrote: > Hi all, > > what is the difference between incb %al and incb $i. According to my > knowledge if you have some thing like "i++" (in c) then it is translated in > to movw $i %ebx, incw %ebx, movw %ebx $i. My question, when I explicitly > give variable as operand to increment in assembly like "incb $i", then will > that instruction execution cycle involves copying the contents from memory > to register and increment and copy back to memory. Is this hidden > and Assembler takes care of it when writing to image file (machine codes or > elf). Another question: Is incb %al is atomic operation, I mean, Is > instruction execution cycle is interrupted by an event or a process. > Thank you. I think it is atomic as long as only one CPU accesses it. But The problem is that on systems with more than one CPU you do not know that happens. There is a "lock prefix" which makes some (all???) instructions atomic. -Michi -- programing a layer 3+4 network protocol for mesh networks see http://michaelblizek.twilightparadox.com -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
