Re: help DMA FIFO buffer

Re: help DMA FIFO buffer

[Alan Cox]

On Iau, 2003-04-10 at 05:18, dave wrote:
> Hi I am writing a device driver LNVRM is uses DMA for commands and data
> i need a function that will wait until their is enough room in the FIFO for
> the new
> data this function works but their must be a better way I need a formula
> that dose
> not have if's in it

Why ?

help DMA FIFO buffer

[dave]

Hi I am writing a device driver LNVRM is uses DMA for commands and data
i need a function that will wait until their is enough room in the FIFO for
the new
data this function works but their must be a better way I need a formula
that dose
not have if's in it

Like this

#define NV04_DMA_WAIT_FREE(free)                 while((dma->size -
(dma->put - dma->control->get)) < free)

thank you .

also it thear is no way can this be made inline ?

void lnvrm_dmaNv04WaitFree(struct _nvxf_dmaChannel dma , unsigned long)
{
  unsigned long get , put = dma->put , size = dma->mask + 1 , free , f = 0 ;

 loop1:
  get = dma->control->Get ;

  if(put < get)
    free = size - (size - get + put) ;
  else
    free = size - (put - get) ;

  if(count <= free) return ; /* Get out as quick as possible */

  if(f) { ErrorF("lnvrm_dmaNv04WaitFree: FIFO FULL free = %8.8lX needed =
%8.8lX\n",free,count) ; f++ }
  goto loop1 ;
}