ia 32 - What happens when memory "wraps" on an IA-32 supporting machine? -



ia 32 - What happens when memory "wraps" on an IA-32 supporting machine? -

i'm creating 64-bit model of ia-32 , representing memory 0-based array of 2**64 bytes (the language i'm modeling in uses ** exponentiation operator). means valid indices array 0 2**64-1. now, model possible modes of accessing memory, 1 can treat 1 element 8-bit number, 2 elements (little-endian) 16-bit number, etc.

my question is, should model if inquire 16-bit (or 32-bit, etc.) number location 2**64-1? right now, model returned value memory(2**64-1) + (8 * memory(0)). i'm not updating flags (which feels wrong). wrapping right behavior? should setting flags when wrapping happens?

i have re-create of intel-64-ia-32-isa.pdf i'm using reference, it's 1,479 pages, , i'm having hard time finding reply particular question.

i tested (did expect that?) 64bit numbers code:

mov dword [0], 0xdeadbeef mov dword [-4], 0x01020304 mov rdi, [-4] phone call writelonghex

in custom os, pages mapped appropriate, running in virtualbox. writelonghex writes rdi screen 16-digit hexadecimal number. result:

so yes, wrap. nil funny happens.

no flags should affected (though manual doesn't no flags should set address wrapping, mov reg, [mem] doesn't impact them ever, , includes case), , no interrupt/trap/whatever happens (unless of course of study 1 or both pages touched not present).

memory ia-32

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