David Gibson <da...@gibson.dropbear.id.au> writes:
> [ Unknown signature status ]
> On Wed, Jul 27, 2016 at 12:56:57AM +0530, Nikunj A Dadhania wrote:
>> From: Vivek Andrew Sha <vivekandrew...@gmail.com>
>>
>> Adds Vector Shift Right Variable instruction.
>>
>> Signed-off-by: Vivek Andrew Sha <vivekandrew...@gmail.com>
>> Signed-off-by: Nikunj A Dadhania <nik...@linux.vnet.ibm.com>
>> ---
>> target-ppc/helper.h | 1 +
>> target-ppc/int_helper.c | 17 +++++++++++++++++
>> target-ppc/translate.c | 2 ++
>> 3 files changed, 20 insertions(+)
>>
>> diff --git a/target-ppc/helper.h b/target-ppc/helper.h
>> index 9703f85..8eada2f 100644
>> --- a/target-ppc/helper.h
>> +++ b/target-ppc/helper.h
>> @@ -211,6 +211,7 @@ DEF_HELPER_3(vslw, void, avr, avr, avr)
>> DEF_HELPER_3(vsld, void, avr, avr, avr)
>> DEF_HELPER_3(vslo, void, avr, avr, avr)
>> DEF_HELPER_3(vsro, void, avr, avr, avr)
>> +DEF_HELPER_3(vsrv, void, avr, avr, avr)
>> DEF_HELPER_3(vslv, void, avr, avr, avr)
>> DEF_HELPER_3(vaddcuw, void, avr, avr, avr)
>> DEF_HELPER_3(vsubcuw, void, avr, avr, avr)
>> diff --git a/target-ppc/int_helper.c b/target-ppc/int_helper.c
>> index 412398f..f4776f0 100644
>> --- a/target-ppc/int_helper.c
>> +++ b/target-ppc/int_helper.c
>> @@ -1722,6 +1722,23 @@ void helper_vslv(ppc_avr_t *r, ppc_avr_t *a,
>> ppc_avr_t *b)
>> }
>> }
>>
>> +void helper_vsrv(ppc_avr_t *r, ppc_avr_t *a, ppc_avr_t *b)
>> +{
>> + int i;
>> + unsigned int shift, bytes, src[ARRAY_SIZE(r->u8) + 1];
>> +
>> + src[0] = 0;
>> + for (i = 0; i < ARRAY_SIZE(r->u8); i++) {
>> + src[i + 1] = a->u8[i];
>> + }
>> +
>> + for (i = 0; i < ARRAY_SIZE(r->u8); i++) {
>> + shift = b->u8[i] & 0x7; /* extract shift value */
>> + bytes = (src[i] << 8) + src[i + 1]; /* extract adjacent bytes */
>
> I think you should be able to construct bytes on the fly without
> pre-generating teh whole of src, as you already did for vslv.
Had done that, but that introduces a bug like this, for eg:
vslv vra,vra,vrb
So modified vra->u8[i] is used during subsequent operation as input.
Assuming I take care or special casing "0":
bytes = ((vra->u8[i - 1] << 8) | (vra->u8[i]))
vra->u8[i] = (bytes >> shift) & 0xFF;
when i = 1, bytes will ((vra->u8[0] << 8) | (vra->u8[1])). But vra->u8[0],
was changed in the previous operation.
Thats the reason src[] is needed
Regards
Nikunj
