qdosmsq:traps:trap_1:hdop
Table of Contents
MT_IPCOM/SMS_HDOP
This trap communicates with the 8049 IPC chip on a QL. This Trap activates sound via SMSQ/E.
| Call Parameters | Return Parameters | ||
|---|---|---|---|
| D0.B | $11 | D0.L | Corrupted? |
| D1.L | Unused. | D1.B | Return parameter. |
| D5.L | Unused. | D5.L | Corrupted. |
| D7.L | Unused. | D7.L | Corrupted. |
| A3.L | Pointer to command string. | A3.L | Preserved. |
Errors
No errors are returned by this trap.
Notes
- All registers not shown above are not used on entry and are preserved on exit.
- The command string to which A3.L points is shown in more detail below. It consists of a command followed by the number of parameters, codes for the parameters, the parameters themselves and a code for the returned parameter.
- There are only three commands useful for an application programmer. These are to start or stop sound and to read the keyboard.
Command String
| Length | Item |
|---|---|
| Byte | Command |
| Byte | Number of parameters |
| Long | Codes for each parameter |
| Byte | 1st parameter |
| Byte | 2nd parameter |
| .. | .. |
| Byte | Code for the reply |
The codes are each two bits long and indicate whether 0, 4 or 8 bits of each parameter are to be transferred. The value of the codes is:
| Value | Meaning |
|---|---|
| %00 | 4 bits (least significant) |
| %01 | 0 bits |
| %10 | 8 bits |
| %11 | 0 bits |
The codes for the parameters to be sent to the IPC are in a long word, which allows up to 16 parameters. The code for the first word is in the least significant two bits of the long word (bits 1 and 0), the code for the next parameter is in the next two bits (bits 3 and 2) and so on.
The code for the returned parameter is in the least significant two bits of the byte containing it.
Commands
Read the Keyboard
| Command | $09 |
| Number of parameters | 1 |
| Long word of codes | $00000000 |
| Parameter | Keyboard row |
| Reply code | $02 |
Initiate Sound
| Command | $0A |
| Number of parameters | 8 |
| Long word of codes | $0000AAAA |
| Parameter 1 | Pitch 1 |
| Parameter 2 | Pitch 2 |
| Parameters 3 & 4 | Interval between steps |
| Parameters 5 & 6 | Duration |
| Parameter 7 MSN | Step in pitch |
| Parameter 7 LSN | Wrap |
| Parameter 8 MSN | Randomness |
| Parameter 8 LSN | Fuzziness |
| Reply code | $01 |
Here MSN means Most significant Nibble and LSN means Least Significant Nibble.
Kill sound
| Command | $0B |
| Number of parameters | 0 |
| Long word of codes | $00000000 |
| Reply code | $01 |
qdosmsq/traps/trap_1/hdop.txt · Last modified: 2010/11/07 17:25 by george.gwilt
