Re: [PATCH 4/5] powerpc/lib/sstep: Add prty instruction emulation
From: Segher Boessenkool <hidden>
Date: 2017-07-13 07:38:04
On Thu, Jul 13, 2017 at 01:25:47PM +1000, Matt Brown wrote:
+static nokprobe_inline void do_prtyw(struct pt_regs *regs, unsigned long v,
+ int ra)
+{
+ unsigned long low, high, out;
+ unsigned int i;
+
+ high = 0;
+ low = 0;
+ out = 0;
+
+ for (i = 0; i < 8; i++) {
+ if (v & (1 << (i * 8)))1UL
+ (i < 4) ? (low++) : (high++); + } + + if (low % 2) + out |= low; + if (high % 2) + out |= (high << 32);
Only the low bit of each word of the output can be set. Something like out = ((high & 1) << 32) | (low & 1); Segher