On 08/06/2010 03:17 AM, Wei Yongjun wrote:
> If bit offset operands is a negative number, BitOp instruction
> will return wrong value. This patch fix it.
>
> +static void fetch_bit_operand(struct decode_cache *c)
> +{
> + unsigned long mask, byte_offset;
> +
> + if (c->dst.type == OP_MEM) {
> + if (c->src.bytes == 2)
> + c->src.val = (s16)c->src.val;
> + else if (c->src.bytes == 4)
> + c->src.val = (s32)c->src.val;
Better not to update in place, but instead use a local signed variable.
> +
> + mask = ~(c->dst.bytes * 8 - 1);
> +
> + if ((long)c->src.val < 0) {
> + /* negative bit offset */
> + byte_offset = c->dst.bytes +
> + ((-c->src.val - 1) & mask) / 8;
> + c->dst.addr.mem -= byte_offset;
> + } else {
> + /* positive bit offset */
> + c->dst.addr.mem += (c->src.val & mask) / 8;
> + }
> + }
Is the if () really necessary? If division translates to arithmetic
shift right, it might not be needed.
> +}
> +
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
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