deal with grey coding of read and write fifo pointers on 4020

diff --git a/comedi/drivers/cb_pcidas64.c b/comedi/drivers/cb_pcidas64.c
index a8782e85d87f330803ed73c50ae0a0c1470d5c69..773cdc45bfeaab2b4262c32de38d51e03e449b2e 100644 (file)
--- a/comedi/drivers/cb_pcidas64.c
+++ b/comedi/drivers/cb_pcidas64.c
@@ -89,8 +89,8 @@ TODO:
 #include "8255.h"
 #include "plx9080.h"
 
-//#undef PCIDAS64_DEBUG        // disable debugging code
-#define PCIDAS64_DEBUG // enable debugging code
+#undef PCIDAS64_DEBUG  // disable debugging code
+//#define PCIDAS64_DEBUG       // enable debugging code
 
 #ifdef PCIDAS64_DEBUG
 #define DEBUG_PRINT(format, args...)  printk("comedi: " format , ## args )
@@ -1610,59 +1610,21 @@ static int ai_cmd(comedi_device *dev,comedi_subdevice *s)
 }
 
 // read num_samples from 16 bit wide ai fifo
-static void pio_drain_ai_fifo_16(comedi_device *dev, unsigned int num_samples)
-{
-       comedi_subdevice *s = dev->read_subdev;
-       comedi_async *async = s->async;
-       unsigned int i;
-
-       DEBUG_PRINT(" read %i samples from fifo\n", num_samples);
-
-       private(dev)->ai_count -= num_samples;
-
-       for(i = 0; i < num_samples; i++)
-       {
-               comedi_buf_put(async, readw(private(dev)->main_iobase + ADC_FIFO_REG));
-       }
-}
-
-// read num_samples from 32 bit wide ai fifo of 4020
-static void pio_drain_ai_fifo_32(comedi_device *dev, unsigned int num_samples)
-{
-       comedi_subdevice *s = dev->read_subdev;
-       comedi_async *async = s->async;
-       unsigned int i;
-       uint32_t fifo_data;
-
-       DEBUG_PRINT(" read %i samples from fifo\n", num_samples);
-
-       private(dev)->ai_count -= num_samples;
-
-       for(i = 0; i < num_samples / 2; i++)
-       {
-               fifo_data = readl(private(dev)->dio_counter_iobase + ADC_FIFO_REG);
-               comedi_buf_put(async, fifo_data & 0xffff);
-               comedi_buf_put(async, (fifo_data >> 16) & 0xffff);
-       }
-}
-
-// figure out how many samples are in fifo and read them
-static void pio_drain_ai_fifo(comedi_device *dev)
+static void pio_drain_ai_fifo_16(comedi_device *dev)
 {
        comedi_subdevice *s = dev->read_subdev;
        comedi_async *async = s->async;
        comedi_cmd *cmd = &async->cmd;
-       int read_segment, read_index, write_segment, write_index;
+       unsigned int i;
        static const int num_fifo_segments = 4;
-       int num_samples;
        uint16_t prepost_bits;
-
-       // figure out how many samples we should read from board's fifo
+       int read_segment, read_index, write_segment, write_index;
+       int num_samples;
 
        do
        {
-               /* Get most significant bits.  Different boards encode the meaning of these bits
-               * differently, so use a scheme that doesn't depend on encoding */
+               /* Get most significant bits (grey code).  Different boards use different code
+               * so use a scheme that doesn't depend on encoding */
                prepost_bits = readw(private(dev)->main_iobase + PREPOST_REG);
                // get least significant 15 bits
                read_index = readw(private(dev)->main_iobase + ADC_READ_PNTR_REG) & 0x7fff;
@@ -1670,30 +1632,21 @@ static void pio_drain_ai_fifo(comedi_device *dev)
 
                /* if read and write pointers are not on the same fifo segment, read to the
                * end of the read segment */
-               if(board(dev)->layout != LAYOUT_4020)
-               {
-                       read_segment = ADC_UPP_READ_PNTR_CODE(prepost_bits);
-                       write_segment = ADC_UPP_WRITE_PNTR_CODE(prepost_bits);
-                       if(read_segment != write_segment)
-                               num_samples = (board(dev)->fifo_depth / num_fifo_segments) - read_index;
-                       else
-                               num_samples = write_index - read_index;
-               } else
-               {
-                       static const int fifo_ptr_limit = 1 << 15;
-                       read_segment = write_segment = 0;
+               read_segment = ADC_UPP_READ_PNTR_CODE(prepost_bits);
+               write_segment = ADC_UPP_WRITE_PNTR_CODE(prepost_bits);
+               if(read_segment != write_segment)
+                       num_samples = (board(dev)->fifo_depth / num_fifo_segments) - read_index;
+               else
                        num_samples = write_index - read_index;
-                       if(num_samples < 0) num_samples += fifo_ptr_limit;
-                       // 4020 stores two samples per fifo entry
-                       num_samples *= 2;
-               }
 
                if(cmd->stop_src == TRIG_COUNT)
                {
+                       if(private(dev)->ai_count == 0) break;
                        if(num_samples > private(dev)->ai_count)
                        {
                                num_samples = private(dev)->ai_count;
                        }
+                       private(dev)->ai_count -= num_samples;
                }
 
                if(num_samples < 0)
@@ -1702,18 +1655,59 @@ static void pio_drain_ai_fifo(comedi_device *dev)
                        break;
                }
 
-               if(board(dev)->layout == LAYOUT_4020)
-               {
-                       pio_drain_ai_fifo_32(dev, num_samples);
-               }else
-                       pio_drain_ai_fifo_16(dev, num_samples);
+               DEBUG_PRINT(" read %i samples from fifo\n", num_samples);
 
-               if(cmd->stop_src == TRIG_COUNT && private(dev)->ai_count <= 0)
+               for(i = 0; i < num_samples; i++)
                {
-                       break;
+                       comedi_buf_put(async, readw(private(dev)->main_iobase + ADC_FIFO_REG));
                }
 
        } while (read_segment != write_segment);
+}
+
+// read from 32 bit wide ai fifo of 4020 - deal with insane grey coding of pointers
+static void pio_drain_ai_fifo_32(comedi_device *dev)
+{
+       comedi_subdevice *s = dev->read_subdev;
+       comedi_async *async = s->async;
+       comedi_cmd *cmd = &async->cmd;
+       unsigned int i;
+       unsigned int max_transfer = 1e5;
+       uint32_t fifo_data;
+       int write_code = readw(private(dev)->main_iobase + ADC_WRITE_PNTR_REG) & 0x7fff;
+       int read_code = readw(private(dev)->main_iobase + ADC_READ_PNTR_REG) & 0x7fff;
+
+       if(cmd->stop_src == TRIG_COUNT)
+       {
+               if(max_transfer > private(dev)->ai_count)
+               {
+                       max_transfer = private(dev)->ai_count;
+               }
+       }
+       for(i = 0; read_code != write_code && i < max_transfer; )
+       {
+               fifo_data = readl(private(dev)->dio_counter_iobase + ADC_FIFO_REG);
+               comedi_buf_put(async, fifo_data & 0xffff);
+               i++;
+               if(i < max_transfer)
+               {
+                       comedi_buf_put(async, (fifo_data >> 16) & 0xffff);
+                       i++;
+               }
+               read_code = readw(private(dev)->main_iobase + ADC_READ_PNTR_REG) & 0x7fff;
+       }
+}
+
+// empty fifo
+static void pio_drain_ai_fifo(comedi_device *dev)
+{
+       comedi_async *async = dev->read_subdev->async;
+
+       if(board(dev)->layout == LAYOUT_4020)
+       {
+               pio_drain_ai_fifo_32(dev);
+       }else
+               pio_drain_ai_fifo_16(dev);
 
        async->events |= COMEDI_CB_BLOCK;
 }