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The value that is programmed into this register indicates the desired threshold vacancy level in 32-bit words in the trace memory. When the available space in the FIFO is less than or equal to this value, that is, fill level >= (MEM_SIZE- BUFWM), the full output is asserted and the STS.Full bit is set. This register is used only in the FIFO modes, that is, SWF1, SWF2, and HWF modes. In CB mode, the same functionality is obtained by programming the RWP to the desired vacancy trigger level, so that when the pointer wraps around, the full output gets asserted indicating that the vacancy level has fallen below the desired level. Reading this register returns the programmed value. The maximum value that can be written into this register is MEM_SIZE- 1, in which case the full output is asserted after the first 32-bit word is written to trace memory. Writing to this register other than when in Disabled state results in UNPREDICTABLE behavior. Any software using it must program it with an initial value before setting the CTL.TraceCaptEn bit to 1.
The BUFWM register characteristics are:
The following figure shows the bit assignments.
The following table shows the bit assignments.
Table 9-302 BUFWM register bit assignments
Read-As-Zero, Writes Ignored.
Buffer Level Watermark. Indicates the desired threshold vacancy level in 32-bit words in the trace memory. The width of the register is log2(MEM_SIZE).