Unlike normal microcodes which are assembled at the time of shipping, S2DEX provides a microcode for use during debugging. The relationship between these two microcodes is the same as the relationship between libultra_rom.a and libultra_d.a.
The debugging microcode S2DEX_D has a slower processing speed than the normal microcode, but has the following functions.
Checking the display list processing log makes it particularly easy to trace the causes of RSP breakdowns, etc.
An output buffer for the RSP display list processing log must be prepared in order to use S2DEX_D. This requires an area which is only the same length as the display list. In addition, it must be aligned on 8 bytes.
Once this area is reserved, set a pointer to the head of the area in the data_size member variable of the OSTask structure. This member variable is not used by either the S2DEX or F3DEX series to mean the essential DL size. Merely a vestigial remnant of the Ver. 1.0 of the N64 Development Library, it is commonly used as the output buffer for the log.
This address must not be the Segment address. If gspS2DEX.fifo_d.o is subsequently started as the microcode, the processing log will be stored in the specified address.
As for the method of displaying the processing log, please refer to the function ucDebugGfxLogPrint() in the included sample program uc_assert.c. In addition, please refer to ucCheckAssert() in the same file regarding determining whether the RSP has stopped.