6. Debugging techniques

Status area

Sequence playback mode and status

During playback of the sequence, the current state is written to the mode status area at any time. To find out what the sequence playback is currently in, see the mode status area.
The mode status area corresponds to pronunciation control numbers 0 to 7, and has a total of 16 bytes for 2 bytes x 8 sequences. For details on the area address, refer to the section on host interface work in the system area.

[Sequence playback mode]

0x00	initial state
0x01	Playing
0x03	Pause during playback
0x05	Fading

[Sequence playback status]

0x00	normal
0x80	The resolution exceeds the capabilities of SEGA SATURN.
0x81	There is no tempo data.
0x82	There is no event data.
0x83	The tempo data is set out of range.
0x84	There is no control in the sequence data
0x85	You specified a bank that does not exist.
0x86	You specified a program that does not exist.
0x87	The program was changed when the bank was not set. When a 0X85 error occurs, it seems that this error often occurs continuously.
0x88	The Volume bias value is too large for the Total level.
0x89	A mixer change was made for a bank that does not exist.
0x8A	I used MONO MODE
0x8B	Layer is not set on the Tone editor.
0x8C	The oldest key-on was forcibly crushed because the number of simultaneous pronunciations exceeded 32.
0x8D	You specified a layer that does not exist.
0x8E	Trouble occurs in DSP
0x8F	Issued an unsupported MIDI event.
0x92	There was a note that could not be pronounced because there were too many FM sound channel.
0x93	Double assignment of slot (program error)
0x94	I tried to play on a MIDI channel other than 1-16.
0x99	NOTE ON was canceled because all slots were filled with FM.

CD-DA input level

Note: This process imposes a load on the sound driver, so if level detection is no longer required, issue the "Digital Audio In Input Level Analysis End (0Bh)" command to end level detection.

+0	PCM stream playback position (0-15)
+1	unused

The data position currently being played. The number of relative samples from the beginning of the PCM stream playback buffer, with values ranging from 0 to 15. Since it is possible to monitor in 4K sample units (4KB units for 8-bit playback and 8KB units for 16-bit playback), an advance of 1 means that the playback position has advanced by 4K samples. Also, even in stereo playback, Rch and Lch have the same playback address.
The PCM stream playback position area corresponds to stream playback numbers 0 to 7, and has a total of 16 bytes for 2 bytes x 8 streams. For details on the area address, refer to the section on host interface work in the system area.

+0	Sequence playback position (H)
+1	Sequence playback position (L)

During sequence playback, the sequence playback position is stored in this area. Values from 0 to FFFFh are stored sequentially. This shows the time from the start of playback, and is a guide to know which position is being played. The value advances by 1 every 100 msec.
The sequence playback position area corresponds to pronunciation control numbers 0 to 7, and has a total of 16 bytes for 2 bytes x 8 sequences. For details on the area address, refer to the section on host interface work in the system area.

Note: Since the sequence playback position is absolute time, the indicated position will change even if the value changes as the tempo changes. In order to synchronize accurately with the sequence being played, use a method such as storing a synchronization message in the sequence data.

□ Then, I will introduce the debugging and checking method.

If a sound-related problem occurs, data that may be used as a reference for investigating the cause may be saved, so check the area below.

○ Error status bitmap

If an error occurs during the operation of the sound driver, the error bit corresponding to the content of the error is set in the system interface table (4 bytes from 420h). Please refer to the section "5 Error Status Bitmap" for details.

○ History of sound control commands

The history of sound control commands is stored in the reserved area of the system area (2048 bytes from 800h to FFFh). Control commands (16 bytes) received from the main system by the sound driver and executed by the sound driver are written in this area at any time in the order in which they were executed.
Writing is done in a ring buffer format, and when the area is full, it is rewritten in order from the oldest one, and the latest 128 commands are always recorded. (If the command processing exceeds 128, it will be overwritten in order from the beginning of the area.) Even in such a case, the writing position of the next data is FFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFF. Therefore, you can see the position of the last written data.
Since the elapsed time from the previous command processing is stored in the 15th and 16th bytes (words) in the command history (16 bytes), it is also possible to verify the temporal timing of command issuance. One count is about 2 msec.

• If there is no sound, is the correct command issued from the main system?
• Is the same command issued multiple times?
• Whether the commands are issued in the correct order due to processing in which the order of the commands is determined.
• Are many commands issued at unusually short intervals?