Hi All,
I've been working on macfb.c, and I notice that it is full of stuff like
this:
/* the nop's are there to order writes. */
nubus_writeb(_regno, &cmap_regs->addr); nop();
nubus_writeb(_red, &cmap_regs->lut); nop();
nubus_writeb(_green, &cmap_regs->lut); nop();
nubus_writeb(_blue, &cmap_regs->lut);
Timing aside, I don't see what are the nop's are for. I thought accessors
like nubus_write/raw_out/out are intended to issue these writes in order
anyway?
And why were nop's were used instead of an empty asm() or just a volatile
qualifier anyway? Some accident of history like a compiler bug?
Also, can a nop provide a useful timing constraint when bus speed can vary
so much from one machine to another?
I'm baffled.
Finn
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