1 main.c
#include "led.h" #define BASE_ADDRESS (volatile datum *) 0x10000000
#define NUM_BYTES 0x10000 /**********************************************************************
*
* Function: main()
*
* Description: Test the second 64 KB bank of SRAM.
*
* Notes:
*
* Returns: 0 on success.
* Otherwise -1 indicates failure.
*
**********************************************************************/
main(void)
{
if ((memTestDataBus(BASE_ADDRESS) != ) ||
(memTestAddressBus(BASE_ADDRESS, NUM_BYTES) != NULL) ||
(memTestDevice(BASE_ADDRESS, NUM_BYTES) != NULL))
{
toggleLed(LED_RED);
return (-);
}
else
{
toggleLed(LED_GREEN);
return ();
} } /* main() */
1.1 Data bus test
// typedef unsigned char datum; /* Set the data bus width to 8 bits. */
/**********************************************************************
*
* Function: memTestDataBus()
*
* Description: Test the data bus wiring in a memory region by
* performing a walking 1's test at a fixed address
* within that region. The address (and hence the
* memory region) is selected by the caller.
*
* Notes:
*
* Returns: 0 if the test succeeds.
* A non-zero result is the first pattern that failed.
*
**********************************************************************/
datum
memTestDataBus(volatile datum * address)
{
datum pattern;
/*
* Perform a walking 1's test at the given address.
*/
for (pattern = ; pattern != ; pattern <<= )
{
/*
* Write the test pattern.
*/
*address = pattern;
/*
* Read it back (immediately is okay for this test).
*/
if (*address != pattern)
{
return (pattern);
}
}
return ();
} /* memTestDataBus() */
1.2 Address bus test
/**********************************************************************
*
* Function: memTestAddressBus()
*
* Description: Test the address bus wiring in a memory region by
* performing a walking 1's test on the relevant bits
* of the address and checking for aliasing. This test
* will find single-bit address failures such as stuck
* -high, stuck-low, and shorted pins. The base address
* and size of the region are selected by the caller.
*
* Notes: For best results, the selected base address should
* have enough LSB 0's to guarantee single address bit
* changes. For example, to test a 64-Kbyte region,
* select a base address on a 64-Kbyte boundary. Also,
* select the region size as a power-of-two--if at all
* possible.
*
* Returns: NULL if the test succeeds.
* A non-zero result is the first address at which an
* aliasing problem was uncovered. By examining the
* contents of memory, it may be possible to gather
* additional information about the problem.
*
**********************************************************************/
datum * memTestAddressBus(volatile datum * baseAddress, unsigned long nBytes)
{
unsigned long addressMask = (nBytes/sizeof(datum) - );
unsigned long offset;
unsigned long testOffset;
datum pattern = (datum) 0xAAAAAAAA;
datum antipattern = (datum) 0x55555555;
/*
* Write the default pattern at each of the power-of-two offsets.
*/
for (offset = ; (offset & addressMask) != ; offset <<= )
{
baseAddress[offset] = pattern;
}
/*
* Check for address bits stuck high.
*/
testOffset = ;
baseAddress[testOffset] = antipattern;
for (offset = ; (offset & addressMask) != ; offset <<= )
{
if (baseAddress[offset] != pattern)
{
return ((datum *) &baseAddress[offset]);
}
}
baseAddress[testOffset] = pattern;
/*
* Check for address bits stuck low or shorted.
*/
for (testOffset = ; (testOffset & addressMask) != ; testOffset <<= )
{
baseAddress[testOffset] = antipattern;
if (baseAddress[] != pattern)
{
return ((datum *) &baseAddress[testOffset]);
}
for (offset = ; (offset & addressMask) != ; offset <<= )
{
if ((baseAddress[offset] != pattern) && (offset != testOffset))
{
return ((datum *) &baseAddress[testOffset]);
}
}
baseAddress[testOffset] = pattern;
}
return (NULL);
} /* memTestAddressBus() */
1.3 Device test
/**********************************************************************
*
* Function: memTestDevice()
*
* Description: Test the integrity of a physical memory device by
* performing an increment/decrement test over the
* entire region. In the process every storage bit
* in the device is tested as a zero and a one. The
* base address and the size of the region are
* selected by the caller.
*
* Notes:
*
* Returns: NULL if the test succeeds. Also, in that case, the
* entire memory region will be filled with zeros.
*
* A non-zero result is the first address at which an
* incorrect value was read back. By examining the
* contents of memory, it may be possible to gather
* additional information about the problem.
*
**********************************************************************/
datum * memTestDevice(volatile datum * baseAddress, unsigned long nBytes)
{
unsigned long offset;
unsigned long nWords = nBytes / sizeof(datum);
datum pattern;
datum antipattern;
/*
* Fill memory with a known pattern.
*/
for (pattern = , offset = ; offset < nWords; pattern++, offset++)
{
baseAddress[offset] = pattern;
}
/*
* Check each location and invert it for the second pass.
*/
for (pattern = , offset = ; offset < nWords; pattern++, offset++)
{
if (baseAddress[offset] != pattern)
{
return ((datum *) &baseAddress[offset]);
}
antipattern = ~pattern;
baseAddress[offset] = antipattern;
}
/*
* Check each location for the inverted pattern and zero it.
*/
for (pattern = , offset = ; offset < nWords; pattern++, offset++)
{
antipattern = ~pattern;
if (baseAddress[offset] != antipattern)
{
return ((datum *) &baseAddress[offset]);
}
}
return (NULL);
} /* memTestDevice() */
