
.origin 0                        // start of program in PRU memory
.entrypoint START                // program entry point for the debugger

#define CLOCK_CNTR_ADDR      0x00000000
#define ADC_STATE_ADDR       0x00000004
#define ADC_CNTRL_STR_ADDR   0x00000008
#define ADC_CNTRL_CHANGE     0x0000000C
#define ADC_ADDR             0x00000010
#define ADC_SIZE             0x00000014
#define ADC_SAMPLE_DIVISOR   0x00000018
#define ADC_NUM_BLOCKS       0x0000001C

#define BUFSIZE              0x20000     // 128K is optimal flash write size for bbone.
#define NUMBUFS              8           // 1Mb shared memory space divided into 8 buffers
#define SHARED_MEM_SIZE      0x100000 

#define BUF_HDR_SIZE         32          // 32 Byte header contained at start of 128k buffer


#define SAMPLE_SIZE          24


#define PRU0_R31_VEC_VALID 32    // allows notification of program completion
#define PRU_EVTOUT_0    3        // the event number that is sent back

//      This map documents pin mapping to the ADS1287, and the associated registers
//      r30.t0  Power Down 8             Pin 8.45 
//      r30.t1  Power Down 4             Pin 8.46
//      r30.t2  Power Down 7             Pin 8.43  
//      r30.t3  Power Down 3             Pin 8.44
//      r30.t4  Power Down 6             Pin 8.41
//      r30.t5  Power Down 2             Pin 8.42
//      r30.t6  Power Down 5             Pin 8.39  
//      r30.t7  Power Down 1             Pin 8.40
//      r30.t8  ADS1278 Board Enable     Pin 8.27
//      r30.t9  SPI_CLK                  Pin 8.29
//      r31.t10 SPI DATA IN              Pin 8.28
//      r31.t11 SPI DATA READY           Pin 8.30


//      Register Use 
//      R0      General Purpose / Indexing
//      R1      General Purpose
#define CLOCK_COUNT    r2   //  Clock Counter used to determine SCLOCK frequency
#define RUN_STATE      r3   //  Run State - can turn off data acq via this
#define ADC_CNTRL_STR  r4   //  ADC Control string used to enable/disable daq channels and daq
#define ADC_CHNG_FLG   r5   //  ADC Control Change flag used to indicate a settings change
#define SMPL_BIT_CNTR  r6   //  Sample bit counter, used to count number of bits read
#define CHAN_BITMASK   r7   //  Channel bitmask used to append channel in MSB of the sample
#define SHR_MEM_PTR    r8   //  Pointer to the shared memory buffer used to store data
#define SHR_MEM_SZ     r9   //  Size of shared memory buffer

#define CURRENT_SAMPLE r14
#define CURRENT_BUF    r15  //  Current 128K buffer we are writing to (0 - 9)
#define CUR_BUF_ADRS   r16 //  Memory address of current 128K buffer
#define CUR_BUF_LEFT   r17  //  This is the amount left of the current buffer in bytes
#define _128K          r18  //  128k stored in register
#define NUM_BLOCKS     r19  //  Number of 128k blocks we are going to record                          
#define SAMPLE1        r21  
#define SAMPLE2        r22  
#define SAMPLE3        r23  
#define SAMPLE4        r24 
#define SAMPLE5        r25  
#define SAMPLE6        r26  
#define SAMPLE7        r27  
#define SAMPLE8        r28  
START:

//  Clear all outputs to the ADS 1278 
        CLR     r30.t0
        CLR     r30.t1
        CLR     r30.t2
        CLR     r30.t3
        CLR     r30.t4
        CLR     r30.t5
        CLR     r30.t6
        CLR     r30.t7
        CLR     r30.t8


// Clear all registers we are going to use, since we know that they can come up 
// with garbage in them 
        MOV     r0, 0 
        MOV     r1, 0
        MOV     CLOCK_COUNT, 0     // R2
        MOV     RUN_STATE, 0     // R3
        MOV     ADC_CNTRL_STR, 0   // R4 
        MOV     ADC_CHNG_FLG, 0    // R5 
        MOV     SMPL_BIT_CNTR, 0   // R6 
        MOV     CHAN_BITMASK, 0    // R7
        MOV     SHR_MEM_PTR, 0     // R8 
        MOV     SHR_MEM_SZ, 0      // R9
        MOV     SKIP_CHN_BM, 0     // R10 
        MOV     CURRENT_SAMPLE, 0  // R11 
        MOV     DROP_SMPL_CNTR, 0  // R12
        MOV     CURRENT_CHAN, 0    // R13 
        MOV     SAMPLE_DIVISOR, 0  // R14
        MOV     SKIP_WRITE, 0      // R15
        MOV     CURRENT_BUF, 0     // R16
        MOV     CUR_BUF_ADRS, 0   // R17
        MOV     CUR_BUF_LEFT, 0    // R18
        MOV     _128K, 0           // R19
        MOV     NUM_BLOCKS, 0      // R20
        MOV     SAMPLE1    , 0     // R21
		MOV     SAMPLE2    , 0     // R21
		MOV     SAMPLE3    , 0     // R21
		MOV     SAMPLE4    , 0     // R21
		MOV     SAMPLE5    , 0     // R21
		MOV     SAMPLE6    , 0     // R21
		MOV     SAMPLE7    , 0     // R21
		MOV     SAMPLE8    , 0     // R21

// Enable the OCP master port -- allows transfer of data to Linux userspace
        LBCO    r0, C4, 4, 4     // load PRU-ICSS CFG reg into r0 
        CLR     r0, r0, 4        // clear bit 4 (STANDBY_INIT)
        SBCO    r0, C4, 4, 4     // store the modified r0 back at the load addr
 
START_LOOP:                                    // This is an easy place to halt the debugger
		MOV	r1,ADC_STATE_ADDR	 
		LBBO	RUN_STATE, r1, 0, 4	       // the daq state is now loaded into r3. 
        QBEQ    START_LOOP, RUN_STATE, 0      // We hang out in a loop until told to read the adc

		MOV	r1,ADC_ADDR	 // 
		LBBO    SHR_MEM_PTR, r1, 0, 4     // load the Linux address that is passed into r8 -- to store sample values

		MOV	r1,ADC_SIZE	 //
		LBBO	SHR_MEM_SZ, r1, 0, 4	 // load the size that is passed into r9 -- the number of samples to take
 
		MOV	r1,ADC_NUM_BLOCKS	 //
		LBBO	NUM_BLOCKS, r1, 0, 4	 // load the count of how many 128K blocks we are going to record 

        MOV     _128K, BUFSIZE
        
        MOV     r1, SHARED_MEM_SIZE       // Check to see that the shared mem size is correct.
        QBEQ    MEM_BUF_ALLOCATED, SHR_MEM_SZ, r1
        HALT    // If the buffer is not allocated, halt.
        
MEM_BUF_ALLOCATED:        
        MOV    CUR_BUF_LEFT, _128K

		MOV	r1,ADC_CNTRL_CHANGE       // load the base address into r1
		LBBO	ADC_CHNG_FLG, r1, 0, 4	  // the ADC_CNTL_CHANGE is now loaded into R5 


        QBBS   CONFIG_CHANGE, ADC_CHNG_FLG.t0     // If bit 1 of ADC_CTRL_CHANGE is set, there is a config
                                        //change
        QBA    CONFIG_DONE              // Else no changes, goto CONFIG_DONE

CONFIG_CHANGE:
		MOV	r1, CLOCK_CNTR_ADDR	 
		LBBO	CLOCK_COUNT, r1, 0, 4	         // the clock delay is now loaded into r2. 

        MOV     r1, ADC_SAMPLE_DIVISOR   // load the sample divisor into R14
        LBBO    SAMPLE_DIVISOR, r1, 0, 4

		MOV	r1,ADC_CNTRL_STR_ADDR	
		LBBO	ADC_CNTRL_STR, r1, 0, 4	         // the ADC_CNTL_STR is now loaded into R4 
        MOV     r30.b0, 0                // Clear all of the power down pins
        CLR     ADC_CHNG_FLG.t1                    // Clear the change flag so we dont do the config every loop


ENABLE_ADC_BOARD:
        QBBS    ENABLE_ADC, ADC_CNTRL_STR.t8              // 
        QBA     RESET_DONE
ENABLE_ADC:
        CLR     r30.t8    // We turn off the DAQ to make sure that we clear it.
        MOV     r0, 0xFF           // Load a delay val into R0
RESET_WAIT:
        SUB     r0, r0, 1        
        QBNE    RESET_WAIT, r0, 0   // loop until the delay has expired (equals 0)
        SET     r30.t8
RESET_DONE:

        QBBS    SET_PWDN1, ADC_CNTRL_STR.t0         // If bit 1 of ADC_CTRL_STR is 1, set PWDN4, Pin 46.  
        QBA     PWDN2
SET_PWDN1: 
		SET     r30.t1

PWDN2:
        QBBS    SET_PWDN2, ADC_CNTRL_STR.t1              // If bit 2 of ADC_CTRL_STR is 1, set PWDN8, pin 45
        QBA     PWDN3
SET_PWDN2:
		SET     r30.t0

PWDN3:
        QBBS    SET_PWDN3, ADC_CNTRL_STR.t2              // If bit 3 of ADC_CTRL_STR is 1, set PWDN3 , pin 44
        QBA     PWDN4
SET_PWDN3:
		SET     r30.t3

PWDN4:
        QBBS    SET_PWDN4, ADC_CNTRL_STR.t3              // If bit 4 of ADC_CTRL_STR is 1, set PWDN7, pin 43
        QBA     PWDN5
SET_PWDN4:
		SET     r30.t2

PWDN5:
        QBBS    SET_PWDN5, ADC_CNTRL_STR.t4              // If bit 5 of ADC_CTRL_STR is 1, set PWDN2, pin 42
        QBA     PWDN6
SET_PWDN5:
		SET     r30.t5

PWDN6:
        QBBS    SET_PWDN6, ADC_CNTRL_STR.t5              // If bit 6 of ADC_CTRL_STR is 1, set PWDN6, Pin 41
        QBA     PWDN7
SET_PWDN6:
		SET     r30.t4

PWDN7:
        QBBS    SET_PWDN7, ADC_CNTRL_STR.t6              // If bit 7 of ADC_CTRL_STR is 1, set PWDN1, Pin 40 
        QBA     PWDN8
SET_PWDN7:
		SET     r30.t7

PWDN8:
        QBBS    SET_PWDN8, ADC_CNTRL_STR.t7              // If bit 8 of ADC_CTRL_STR is 1, set PWDN5, Pin 39
        QBA     CONFIG_DONE
SET_PWDN8:
    SET     r30.t6


CONFIG_DONE:

//  We have just reset and then enabled the ADC, and enabled channels`. Wait a little bit before we try to read samples.
        MOV     r0, 0x0F           // Load a delay val into R0
INIT_WAIT:
        SUB     r0, r0, 1        
        QBNE    INIT_WAIT, r0, 0   // loop until the delay has expired (equals 0)
       

//We kick off a clock pulse so we can see it on the logic analyzer for debug purposes
		SET 	r30.t9		 // set the clock to be low
        MOV     r0, CLOCK_COUNT           // Reload the clock delay val into R0
DELAY_ON1:
        SUB     r0, r0, 1        
        QBNE    DELAY_ON1, r0, 0   // loop until the delay has expired (equals 0)

        MOV     r0, CLOCK_COUNT           // Reload the clock delay val into R0
		CLR	r30.t9		 // set the clock to be low

DELAY_OFF1:
        SUB     r0, r0, 1        
        QBNE    DELAY_OFF1, r0, 0   // loop until the delay has expired (equals 0)
        MOV     r0, CLOCK_COUNT           // Reload the clock delay val into R0


//We want to look at the first bit in the config bitmask.
READ_NEXT_SAMPLE:
		MOV	r1,ADC_STATE_ADDR    //Check to see if we are still need to be running	  
		LBBO	RUN_STATE, r1, 0, 4	       
        QBEQ    CONTINUE_DAQ, RUN_STATE, 1      
        HALT  // We've been told to stop.

CONTINUE_DAQ:
        MOV     CHAN_BITMASK, 1
        MOV     CURRENT_CHAN, 0
		MOV     SMPL_BIT_CNTR, SAMPLE_SIZE  // We're going to read 24 bits        
		MOV		SAMPLE1, 0
		MOV		SAMPLE2, 0
		MOV		SAMPLE3, 0
		MOV		SAMPLE4, 0
		MOV		SAMPLE5, 0
		MOV		SAMPLE6, 0
		MOV		SAMPLE7, 0
		MOV		SAMPLE8, 0

// We check data ready to make sure the ADC has had a chance to initialize and set dready high before sampling.
DATA_READY_HIGH:
        QBBS    DATA_READY_WAIT, R31.t11
        QBA     DATA_READY_HIGH

DATA_READY_WAIT:
        QBBC    DATA_READY, r31.t11  // If Data Ready line clear, read a sample
        QBA     DATA_READY_WAIT      // Else hang out in a tight loop ...

DATA_READY:
READ_CHANNEL1:
        MOV     r0, CLOCK_COUNT      // Reload the clock delay val into R0
		SET	r30.t9					 // set the clock line to be high

DELAYON1:
        SUB     r0, r0, 1        
        QBNE    DELAYON1, r0, 0   

	    
		CLR	r30.t9		 // set the clock to be low

		// Read Data In 
		QBBC	ZERO_BIT1, r31.t10  // Check to see whether Data In is a 0 or 1
		OR	SAMPLE1, SAMPLE1, 0x00000001

ZERO_BIT1:	
        LSL     SAMPLE1, SAMPLE1, 1      // Shift current sample contents left by one

        
		MOV     r0, CLOCK_COUNT
DELAYOFF1:
        SUB     r0, r0, 1        
        QBNE    DELAYOFF, r0, 0   // loop until the delay has expired (equals 0)
		SUB     SMPL_BIT_CNTR, SMPL_BIT_CNTR, 1            // See if we have read all 24 bits of the sample
		QBNE    READ_CHANNEL1, SMPL_BIT_CNTR, 0


//////////////////////////
READ_CHANNEL2:
        MOV     r0, CLOCK_COUNT      // Reload the clock delay val into R0
		SET	r30.t9					 // set the clock to be high

DELAYON2:
        SUB     r0, r0, 1        
        QBNE    DELAYON2, r0, 0   

	               // Reload the clock delay val into R0
		CLR	r30.t9		 // set the clock to be low

		// Read Data In 
		QBBC	ZERO_BIT2, r31.t10  // Check to see whether Data In is a 0 or 1
		OR	SAMPLE2, SAMPLE2, 0x00000001

ZERO_BIT2:	
        LSL     SAMPLE2, SAMPLE2, 1      // Shift current sample contents left by one

        SUB     SMPL_BIT_CNTR, SMPL_BIT_CNTR, 1            // See if we have read all 24 bits of the sample
         
		MOV     r0, CLOCK_COUNT
DELAYOFF21:
        SUB     r0, r0, 1        
        QBNE    DELAYOFF, r0, 0   // loop until the delay has expired (equals 0)
		QBNE    READ_CHANNEL2, SMPL_BIT_CNTR, 0

//////////////////////
READ_CHANNEL3:
        MOV     r0, CLOCK_COUNT      // Reload the clock delay val into R0
		SET	r30.t9					 // set the clock to be high

DELAYON3:
        SUB     r0, r0, 1        
        QBNE    DELAYON3, r0, 0   

	               // Reload the clock delay val into R0
		CLR	r30.t9		 // set the clock to be low

		// Read Data In 
		QBBC	ZERO_BIT3, r31.t10  // Check to see whether Data In is a 0 or 1
		OR	SAMPLE3, SAMPLE3, 0x00000001

ZERO_BIT3:	
        LSL     SAMPLE3, SAMPLE3, 1      // Shift current sample contents left by one

        SUB     SMPL_BIT_CNTR, SMPL_BIT_CNTR, 1            // See if we have read all 24 bits of the sample
         
		MOV     r0, CLOCK_COUNT
DELAYOFF3:
        SUB     r0, r0, 1        
        QBNE    DELAYOFF, r0, 0   // loop until the delay has expired (equals 0)
		QBNE    READ_CHANNEL3, SMPL_BIT_CNTR, 0

/////////////////////////

READ_CHANNEL4:
        MOV     r0, CLOCK_COUNT      // Reload the clock delay val into R0
		SET	r30.t9					 // set the clock to be high

DELAYON4:
        SUB     r0, r0, 1        
        QBNE    DELAYON4, r0, 0   

	               // Reload the clock delay val into R0
		CLR	r30.t9		 // set the clock to be low

		// Read Data In 
		QBBC	ZERO_BIT4, r31.t10  // Check to see whether Data In is a 0 or 1
		OR	SAMPLE4, SAMPLE4, 0x00000001

ZERO_BIT4:	
        LSL     SAMPLE4, SAMPLE4, 1      // Shift current sample contents left by one

        SUB     SMPL_BIT_CNTR, SMPL_BIT_CNTR, 1            // See if we have read all 24 bits of the sample
         
		MOV     r0, CLOCK_COUNT
DELAYOFF4:
        SUB     r0, r0, 1        
        QBNE    DELAYOFF, r0, 0   // loop until the delay has expired (equals 0)
		QBNE    READ_CHANNEL4, SMPL_BIT_CNTR, 0

/////////////////////////
READ_CHANNEL5:
        MOV     r0, CLOCK_COUNT      // Reload the clock delay val into R0
		SET	r30.t9					 // set the clock to be high

DELAYON5:
        SUB     r0, r0, 1        
        QBNE    DELAYON5, r0, 0   

	               // Reload the clock delay val into R0
		CLR	r30.t9		 // set the clock to be low

		// Read Data In 
		QBBC	ZERO_BIT5, r31.t10  // Check to see whether Data In is a 0 or 1
		OR	SAMPLE5, SAMPLE5, 0x00000001

ZERO_BIT5:	
        LSL     SAMPLE5, SAMPLE5, 1      // Shift current sample contents left by one

        SUB     SMPL_BIT_CNTR, SMPL_BIT_CNTR, 1            // See if we have read all 24 bits of the sample
         
		MOV     r0, CLOCK_COUNT
DELAYOFF5:
        SUB     r0, r0, 1        
        QBNE    DELAYOFF, r0, 0   // loop until the delay has expired (equals 0)
		QBNE    READ_CHANNEL5, SMPL_BIT_CNTR, 0

/////////////////////////
READ_CHANNEL6:
        MOV     r0, CLOCK_COUNT      // Reload the clock delay val into R0
		SET	r30.t9					 // set the clock to be high

DELAYON6:
        SUB     r0, r0, 1        
        QBNE    DELAYON6, r0, 0   

	               // Reload the clock delay val into R0
		CLR	r30.t9		 // set the clock to be low

		// Read Data In 
		QBBC	ZERO_BIT6, r31.t10  // Check to see whether Data In is a 0 or 1
		OR	SAMPLE6, SAMPLE6, 0x00000001

ZERO_BIT6:	
        LSL     SAMPLE6, SAMPLE6, 1      // Shift current sample contents left by one

        SUB     SMPL_BIT_CNTR, SMPL_BIT_CNTR, 1            // See if we have read all 24 bits of the sample
         
		MOV     r0, CLOCK_COUNT
DELAYOFF6:
        SUB     r0, r0, 1        
        QBNE    DELAYOFF, r0, 0   // loop until the delay has expired (equals 0)
		QBNE    READ_CHANNEL6, SMPL_BIT_CNTR, 0

/////////////////////////
READ_CHANNEL7:
        MOV     r0, CLOCK_COUNT      // Reload the clock delay val into R0
		SET	r30.t9					 // set the clock to be high

DELAYON7:
        SUB     r0, r0, 1        
        QBNE    DELAYON7, r0, 0   

	               // Reload the clock delay val into R0
		CLR	r30.t9		 // set the clock to be low

		// Read Data In 
		QBBC	ZERO_BIT7, r31.t10  // Check to see whether Data In is a 0 or 1
		OR	SAMPLE7, SAMPLE7, 0x00000001

ZERO_BIT7	
        LSL     SAMPLE7, SAMPLE7, 1      // Shift current sample contents left by one

        SUB     SMPL_BIT_CNTR, SMPL_BIT_CNTR, 1            // See if we have read all 24 bits of the sample
         
		MOV     r0, CLOCK_COUNT
DELAYOFF7:
        SUB     r0, r0, 1        
        QBNE    DELAYOFF, r0, 0   // loop until the delay has expired (equals 0)
		QBNE    READ_CHANNEL7, SMPL_BIT_CNTR, 0

/////////////////////////
READ_CHANNEL8:
        MOV     r0, CLOCK_COUNT      // Reload the clock delay val into R0
		SET	r30.t9					 // set the clock to be high

DELAYON8:
        SUB     r0, r0, 1        
        QBNE    DELAYON8, r0, 0   

	               // Reload the clock delay val into R0
		CLR	r30.t9		 // set the clock to be low

		// Read Data In 
		QBBC	ZERO_BIT8, r31.t10  // Check to see whether Data In is a 0 or 1
		OR	SAMPLE8, SAMPLE8, 0x00000001

ZERO_BIT8:	
        LSL     SAMPLE8, SAMPLE8, 1     // Shift current sample contents left by one

        SUB     SMPL_BIT_CNTR, SMPL_BIT_CNTR, 1            // See if we have read all 24 bits of the sample
         
		MOV     r0, CLOCK_COUNT
DELAYOFF8:
        SUB     r0, r0, 1        
        QBNE    DELAYOFF, r0, 0   // loop until the delay has expired (equals 0)
		QBNE    READ_CHANNEL8, SMPL_BIT_CNTR, 0

/////////////////////////
STORE_SAMPLE:                     
 
        LSR	SAMPLE1, SAMPLE1, 1      // Need to shift the sample word back to the right by one
		LSR	SAMPLE2, SAMPLE2, 1
		LSR	SAMPLE3, SAMPLE3, 1
		LSR	SAMPLE4, SAMPLE4, 1
		LSR	SAMPLE5, SAMPLE5, 1
		LSR	SAMPLE6, SAMPLE6, 1
		LSR	SAMPLE7, SAMPLE7, 1
		LSR	SAMPLE8, SAMPLE8, 1

        MOV     SAMPLE1.b3, 0x01    // Stash the channel bitmask in the upper byte used to store the sample  
		MOV     SAMPLE2.b3, 0X02
		MOV     SAMPLE3.b3, 0x03
		MOV     SAMPLE4.b3, 0x04
		MOV     SAMPLE5.b3, 0x05
		MOV     SAMPLE6.b3, 0x06
		MOV     SAMPLE7.b3, 0x07
		MOV     SAMPLE8.b3, 0x08

		SBBO	SAMPLE1, SHR_MEM_PTR, 0, 4 // store the sample value into shared  memory space
		ADD	SHR_MEM_PTR, SHR_MEM_PTR, 4	 // Add 4  bytes per sample to the address pointer
		
		SBBO	SAMPLE2, SHR_MEM_PTR, 0, 4 // store the sample value into shared  memory space
		ADD	SHR_MEM_PTR, SHR_MEM_PTR, 4	 // Add 4  bytes per sample to the address pointer

		SBBO	SAMPLE3, SHR_MEM_PTR, 0, 4 // store the sample value into shared  memory space
		ADD	SHR_MEM_PTR, SHR_MEM_PTR, 4	 // Add 4  bytes per sample to the address pointer
		 
		SBBO	SAMPLE4, SHR_MEM_PTR, 0, 4 // store the sample value into shared  memory space
		ADD	SHR_MEM_PTR, SHR_MEM_PTR, 4	 // Add 4  bytes per sample to the address pointer

		SBBO	SAMPLE5, SHR_MEM_PTR, 0, 4 // store the sample value into shared  memory space
		ADD	SHR_MEM_PTR, SHR_MEM_PTR, 4	 // Add 4  bytes per sample to the address pointer

		SBBO	SAMPLE6, SHR_MEM_PTR, 0, 4 // store the sample value into shared  memory space
		ADD	SHR_MEM_PTR, SHR_MEM_PTR, 4	 // Add 4  bytes per sample to the address pointer

		SBBO	SAMPLE7, SHR_MEM_PTR, 0, 4 // store the sample value into shared  memory space
		ADD	SHR_MEM_PTR, SHR_MEM_PTR, 4	 // Add 4  bytes per sample to the address pointer

		SBBO	SAMPLE8, SHR_MEM_PTR, 0, 4 // store the sample value into shared  memory space
		ADD	SHR_MEM_PTR, SHR_MEM_PTR, 4	 // Add 4  bytes per sample to the address pointer

		SUB	CUR_BUF_LEFT, CUR_BUF_LEFT, 32	 // reducing the number of samples - 4 bytes per sample, 8 channels
		
		QBEQ	BUFFER_DONE, CUR_BUF_LEFT, 0       // See if we have taken 128kb of samples
 
        QBA     READ_NEXT_SAMPLE  // If we've looped thru all channels in the sample. wait for the next sample


BUFFER_DONE:				 
        // Generate an interrupt to the Linux process to write the buffer to flash

        MOV     r31.b0, PRU0_R31_VEC_VALID | PRU_EVTOUT_0
		
HALT // Debug


        MOV     CUR_BUF_LEFT, _128K

        // If we have recorded all of the buffers that we need to, then halt.
        SUB     NUM_BLOCKS, NUM_BLOCKS, 1
        QBEQ    END, NUM_BLOCKS, 0  

        ADD     CUR_BUF_ADRS, CUR_BUF_ADRS, _128K
        MOV     r1, SHARED_MEM_SIZE       
        QBEQ    WRAP_TIME, CUR_BUF_ADRS, r1 
        QBA     READ_NEXT_SAMPLE

WRAP_TIME:
        // Always wanted to be a rapper ;-0)
        // We have used all the shared memory to write samples, wrap back to the beginning.
        MOV	CUR_BUF_ADRS, 0
        MOV     r31.b0, PRU0_R31_VEC_VALID | PRU_EVTOUT_0
HALT  //DEBUG
        QBA     READ_NEXT_SAMPLE

// halt the pru program -- we reach here when the file is full. 
END:
		HALT                  


