On Fri, Jan 07, 2011 at 02:42:57PM -0800, Richard Henderson wrote:
> Signed-off-by: Richard Henderson <r...@twiddle.net>
> ---
> tcg/README | 14 ++++++++++++++
> tcg/tcg-op.h | 40 ++++++++++++++++++++++++++++++++++++++++
> tcg/tcg-opc.h | 6 ++++++
> tcg/tcg.c | 13 +++++++++++++
> 4 files changed, 73 insertions(+), 0 deletions(-)
>
> diff --git a/tcg/README b/tcg/README
> index 68d27ff..ef59070 100644
> --- a/tcg/README
> +++ b/tcg/README
> @@ -285,6 +285,20 @@ the four high order bytes are set to zero.
> Indicate that the value of t0 won't be used later. It is useful to
> force dead code elimination.
>
> +* deposit_i32/i64 dest, t1, t2, loc
> +
> +Deposit T2 as a bitfield into T1, placing the result in DEST.
> +The bitfield is described by LOC, an immediate value:
> +
> + bits 0:7 - the length of the bitfield
> + bits 8:15 - the position of the first bit
> +
> +For example, 0x101 indicates a 1-bit field at bit 1.
> +This operation would be equivalent to
> +
> + dest = (t1 & ~2) | ((t2 << 1) & 2)
I'm being rather picky, but would something like this be better? :-
For example, 0x804 indicates a 4-bit field starting from bit 8.
This operation would be equivalent to:
dest = (t1 & ~(0xf << 8)) | ((t2 << 8) & (0xf << 8))
OTOH, the code in your version was simpler... so maybe 0x201 or 0x102
as a compromise?
I suppose it's unlikely that anyone's really going to need the example
though, so I'm probably fussing too much. :-)
Cheers,
--
Stuart Brady
