- removed FILE parameter from print_info() (unused - since dbg_printf() doesn't
need it)
- converted tabs to spaces
- TODO: implement 'info device' with optional arguments to get rid of the
print_info() method
It already had limited usability before. With stack direct access optimization the callback won't be called for stack accesses as well.
See note by Brian Slechta:
=== Cut Hete ===
While using Bochs as a reference model for simulations, the simulator needs
information about what loads/stores are taking place with each instruction.
Presumably, that is what the BX_INSTR_MEM_DATA() instrumentation macros
cover (which is the place where our simulator hooks up).
The RETnear_xxx() functions call access_linear() directly, rather than call
read_virtual_xxx() functions. This is a problem for code making use of the
BX_INSTR_MEM_DATA() hook because it does not get called for these
instructions. Should this be changed along with some other instructions
that exhibit this?
=== Cut Hete ===
For Bryan's usage bx_instr_lin_access and bx_instr_phy_read/bx_instr_phy_write callbacks should be used.
in the config interface. Applied settings are marked as 'done' with the value
-1 to avoid unwanted modification. NOTE: Not all Bochs modules exist when
running the start menu / dialog.
but in case you want a few %% of extra emulation performance - it is still possible to disable it with configure option.
most guests I saw do not use it !
for CPU emulation performance reasons, the alignment check compilation
still can be enabled using configure option --enable-alignment-check.
There is no software in the world which enable #AC exception checking, this
x86 feature is completely legacy but its emulation support costs up to 3-5%
emulation speed.
The checking for #AC exception enable still will be done, if
CPL == 3, EFLAGS.AC = 1 and CR0.AM = 1
but the alignment check is not compiled in, the Bochs will PANIC with corresponding message.
You can press 'always continue' and ignore the PANIC, the simulation will continue as if alignment checking is not enabled.
The problem with Parity is it is generally referenced very rarely so the current lazy flags code is not efficient to updated Parify flag only (because it updates low 8 bits of .result value the existing Zero Flag has to be shadowed in .auxbits.
So I flipped it around, to make Parity be shadowed in auxbits. .result now is only needed to derive Zero Flag, and both Sign and Parify are derived from .result + .auxbits (as Zero Flag is now). For the 90% of the conditional jumps that are JZ or JNZ, this is a speedup.
Parity is now derived from 8 bits in .result and 8 bits in .auxbits, and Sign is derived from one flag in .result and 1 bit in .auxbits by XOR-ing them all together. It makes the code sequences for SAHF and POPF simpler too.
