On Wed, May 25, 2016 at 03:34:55AM -0400, George Spelvin wrote: > +static inline u32 __attribute_const__ __hash_32(u32 x) > +{ > + u32 a, b; > + > + asm( "move.l %2,%0" /* 0x0001 */ > + "\n lsl.l #2,%0" /* 0x0004 */ > + "\n move.l %0,%1" > + "\n lsl.l #7,%0" /* 0x0200 */ > + "\n add.l %2,%0" /* 0x0201 */ > + "\n add.l %0,%1" /* 0x0205 */ > + "\n add.l %0,%0" /* 0x0402 */ > + "\n add.l %0,%1" /* 0x0607 */ > + "\n lsl.l #5,%0" /* 0x8040 */ > + /* 0x8647 */
There is no standard way to write asm in the kernel, but I prefer a simple semicolon after each insn asm("move.l %2,%0;" /* 0x0001 */ "lsl.l #2,%0;" /* 0x0004 */ "move.l %0,%1;" "lsl.l #7,%0;" /* 0x0200 */ "add.l %2,%0;" /* 0x0201 */ "add.l %0,%1;" /* 0x0205 */ "add.l %0,%0;" /* 0x0402 */ "add.l %0,%1;" /* 0x0607 */ "lsl.l #5,%0" /* 0x8040 */ /* 0x8647 */ Also, it took me some time to understand the hexadecimal constants in the comments (and the last one predicts a future event :)). > + : "=&d" (a), "=&r" (b) > + : "g" (x)); > + > + return ((u16)(x*0x61c8) << 16) + a + b; > +} Just my two cents Philippe