Start12.c文件解释

// ram test in bootrom
/* 
RAM Test (MBIST) and RAM Initialization
The RAM memory test is performed for cold reset type. 
The RAM initialization is performed for cold and warm reset types.
When executed, the RAM MBIST test destroys the contents  of the tested RAM.It consists of a linear write/read
algorithm using alternating data. 
In case an error is detected in the RAM MBIST, the appropriate error status is captured and the device enters
an endless loop. As the watchdog is enabled when entering the endless error loop after a boot in user or
debugmode, a WDT1 cold reset is asserted after timeout and the RAM test is re-executed. 
After five (5) consecutive  watchdog resets, the device enters SLEEP mode (by hardware function).
The RAM initialization writes the whole RAM to zero with the proper ECC status. This is needed to prevent an
ECC error during user code execution due to a write operation to a non initialized location (with invalid ECC
code). 
Note: The standard RAM interface is disabled during MBIST test execution.

在bootrom中的ram测试
包括RAM测试（MBIST） 和RAM 初始化两种
RAM记忆测试执行于冷复位类型。
RAM初始化执行于冷和热复位类型。
当执行时，RAM MBIST测试破坏了测试的RAM的内容。它包含了一个线性的写/读算法用于交互数据。
假如一个错误在RAM MBIST中被检测到，适当的错误状态被捕获到，然后设备进入
一个无尽循环中。当在引导用户或调试模式之后进入无休止的错误循环时，看门狗被启用。
在超时后一个WDT1冷复位生效并且RAM测试被重新执行。
在5次连续的看门狗复位之后，设备进入SLEEP模式（使用硬件功能）。
RAM的初始化使用适当的ECC状态来将整个RAM写成零。
由于对非初始化位置的写保护（使用无效的ECC代码），在执行代码时，需要防止ECC错误。
注意：在MBIST测试执行时标准的RAM接口被禁用。