The swizzle instruction is very powerful in that in can do any of the
256 permutations of xyzw, optionally negate any combination of the
resulting components, and zero any combination of the result components
(even all). This means the one instruction can take care of any actual
swizzles, conjugation for complex and quaternion values, zeroing vectors
(not that it's the only way), and probably other weird things.
The python file was used to generate the jump table and actual swizzle
code.
They even found a bug in the addressing mode functions :) (I'd forgotten
that I wanted signed offsets from the pointer and thus forgot to cast
st->b to short in order to get the sign extension)
This allows the VM to select the right execution loop and qfcc currently
still produces only the old IS (it doesn't know how to deal with the new
IS yet)
When it's finalized (most of the conversion operations will go, probably
the float bit ops, maybe (very undecided) the 3-component vector ops,
and likely the CALLN ops), this will be the actual instruction set for
Ruamoko.
Main features:
- Significant reduction in redundant instructions: no more multiple
opcodes to move the one operand size.
- load, store, push, and pop share unified addressing mode encoding
(with the exception of mode 0 for load as that is redundant with mode
0 for store, thus load mode 0 gives quick access to entity.field).
- Full support for both 32 and 64 bit signed integer, unsigned integer,
and floating point values.
- SIMD for 1, 2, (currently) 3, and 4 components. Transfers support up
to 128-bit wide operations (need two operations to transfer a full
4-component double/long vector), but all math operations support both
128-bit (32-bit components) and 256-bit (64-bit components) vectors.
- "Interpreted" operations for the various vector sizes: complex dot
and multiplication, 3d vector dot and cross product, quaternion dot
and multiplication, along with qv and vq shortcuts.
- 4-component swizzles for both sizes (not yet implemented, but the
instructions are allocated), with the option to zero or negate (thus
conjugates for complex and quaternion values) individual components.
- "Based offsets": all relevant instructions include base register
indices for all three operands allowing for direct access to any of
four areas (eg, current entity, current stack frame, Objective-QC
self, ...) instructions to set a register and push/pop the four
registers to/from the stack.
Remaining work:
- Implement swizzle operations and a few other stragglers.
= Make a decision about conversion operations (if any instructions
remain, they'll be just single-component (at 14 meaningful pairs,
that's a lot of instructions to waste on SIMD versions).
- Decide whether to keep CALL1-CALL8: probably little point in
supporting two different calling conventions, and it would free up
another eight instructions.
- Unit tests for the instructions.
- Teach qfcc to generate code for the new instruction set (hah, biggest
job, I'm sure, though hopefully not as crazy as the rewrite eleven
years ago).
I wish I'd done it this way years ago (but maybe gcc 2.95 couldn't hack
the casts, I do know there were aliasing problems in the past). Anyway,
this makes operand access much more consistent for variable sized
operands (eg float vs double vs vec4), and is a big part of the new
instruction set implementation.
There is no reasonable way (due to hardware-enforced alignment issues)
to simply convert old bytecode to new (probably best done with an
off-line tool, preferably just recompiling when I get qfcc up to the
job), so both loops will need to be present. This just moves the
original loop into its own function in order to make it easy to bring in
the new (and iron out integration issues).
And add a unary op macro. Having VectorCompOp makes it easy to write
macros that work for multiple data widths, which is why it and its users
now use (dst, ...) instead of (..., dst) as in the past. I'll sort out
the other macros later now that I know the compiler handily gives
messages about the switched order (uninitialized vars etc).
For int, long, float and double. I've been meaning to add them for a
while, and they're part of the new Ruamoko instructions set (which is
progressing nicely).
The opcode table is a nightmare to maintain, but this does clean it up
and speed up opcode lookups since they can now be indexed. Of course, it
turns out I had missed adding several instructions, so had to fix that,
and qfcc needed a bit of a re-jigger to get the opcode out of the table.
The list of all allocated dispatch tables is used to free all the tables
when the progs are reloaded. Not clearing the list meant that the next
instance (second map change) corrupted the list.
Forgetting to unhook the functions (Sys_Printf and the client console's
input event handler) was not a problem for static builds because the
functions were always present, but in builds with dynamic plugins, the
client console's code got ripped away and thus Sys_Printf and the event
hander were being sent into invalid memory. Too much work, not enough
play (with a fully installed client).
The switch from using pr_functions (dfunction_t) to function_table
(bfunction_t) for keeping track of the current function (and thus
profiling data) broke PR_Profile as it never saw anything but 0.
Even NUM_FOR_BAD_EDICT will have a bad day if the edict pointer is
invalid, so make sure that the entity pointer is valid (within the edict
area AND a multiple of edict size).
PR_LoadDebug now does only the initial version and crc checks, and the
byte-swapping of the loaded symbols file. PR_DebugSetSym sets up all the
pointers.
The homogeneous coord was not being initialized and thus was picking up
rubbish from the stack. This is why the test would succeed in some
circumstances but fail in others.
Forgetting to invoke [super dealloc] in a derived class's -dealloc
method has caused me to waste far too much time chasing down the
resulting memory leaks and crashes. This is actually the main focus of
issue #24, but I want to take care of multiple paths before I consider
the issue to be done.
However, as a bonus, four cases were found :)
Fixes axis inputs being half what they should be. Can't quite get +1,
though (need to figure something out for the positive axis range being
slightly smaller than the negative range).
With some hacks that are not included (plan on handling events and
contexts properly), button inputs, including using listeners, are
working nicely: my little game is working again. While the trampoline
code was a bit repetitive (and I do want to clean that up), connecting
button listeners directly to Ruamoko instance methods proved to be quite
nice.
mtwist_rand_0_1 produces numbers in the range [0, 1) and
mtwist_rand_m1_1 produces numbers in the range (-1, 1). The numbers will
not be denormal, so the distribution should be fairly uniform (as much
as Mersenne Twister itself is), but this needs proper testing.
0 is included for the mtwist_rand_0_1 as it seems useful, but -1 is not
included in mtwist_rand_m1_1 in order to keep the extremes of the
distribution balanced around 0.
