Interrupts: Difference between revisions

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(Created page with "The WonderSwan features fourteen different interrupts: * CPU interrupts - six provided by the V30MZ CPU ($00-$05), * Hardware interrupts - eight provided by the SoC's hardware ($00-$07, or $08-$0F, or $10-$1F, or ... $F8-$FF - controlled by an offset <code>V</code>): ** Level - will be reissued so long as the prerequisite condition is raised or the interrupt is disabled, ** Edge - will only be issued once; acknowledging the interrupt prevents reissuing until the conditi...")
 
 
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== Interrupts ==
The WonderSwan features fourteen different interrupts:
The WonderSwan features fourteen different interrupts:


* CPU interrupts - six provided by the V30MZ CPU ($00-$05),
* CPU interrupts - six provided by the V30MZ CPU ($00-$05),
* Hardware interrupts - eight provided by the SoC's hardware ($00-$07, or $08-$0F, or $10-$1F, or ... $F8-$FF - controlled by an offset <code>V</code>):
* Hardware interrupts - eight provided by the SoC's hardware ($00-$07, or $08-$0F, or $10-$1F, or ... $F8-$FF - controlled by an offset <code>V</code>):
** Level - will be reissued so long as the prerequisite condition is raised or the interrupt is disabled,
** Level - will be constantly requested while enabled and the prerequisite condition is true,
** Edge - will only be issued once; acknowledging the interrupt prevents reissuing until the condition is toggled again.
** Edge - will only be requested while enabled the moment the prerequisite condition ''becomes'' true.


The user can additionally define and use any of the 256 interrupt vectors in their own code.
Level interrupts will be immediately retriggered upon acknowledging unless they are disabled, or their prerequisite condition is cleared (for example, a byte is read from the UART). Edge interrupts are only triggered the moment they happen; acknowledging them is sufficient until the next time one is issued (for example, until the next vertical blank).
 
The user can additionally make use of all 256 available interrupt vectors in their own code.


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== I/O ports ==


== I/O Ports ==
{{Anchor|Interrupt Vector Offset}}
=== Interrupt Vector Offset ($B0 write) ===


=== Interrupt Vector ===
<pre>
7  bit  0
---- ----
VVVV V...
|||| |
++++-+---- Interrupt vector offset
</pre>
 
{{Anchor|Interrupt Vector Request}}
 
=== Interrupt Vector Request ($B0 read) ===


<pre>
<pre>
7  bit  0
7  bit  0
---- ----
---- ----
VVVV V...
vvvv vvvv
|||| ||||
|||| ||||
++++-++++- Interrupt vector offset
++++-++++- Interrupt vector requested
           (lowest three bits ignored)
           from the CPU.
</pre>
</pre>


=== Interrupt Enable ===
* Bits <code>7 .. 3</code> of this will always equal the user-provided vector offset.
* Bits <code>2 .. 0</code> of this will always equal the highest set bit index of Interrupt Status; if all bits in Interrupt Status are clear, they will equal <code>0</code>.
 
{{Anchor|Interrupt Enable}}
 
=== Interrupt Enable ($B2) ===


<pre>
<pre>
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</pre>
</pre>


=== Interrupt Status ===
Contrary to other systems, this also controls whether interrupts set the relevant bit in Interrupt Status.
 
{{Anchor|Interrupt Status}}
 
=== Interrupt Status ($B4 read)===


<pre>
<pre>
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</pre>
</pre>


=== Interrupt Acknowledge ===
{{Anchor|Interrupt Acknowledge}}
=== Interrupt Acknowledge ($B6 write)===


<pre>
<pre>
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</pre>
</pre>


=== Interrupt NMI Control ===
{{Anchor|Interrupt NMI Control}}
=== Interrupt NMI Control ($B7)===


<pre>
<pre>
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---- ----
---- ----
...b ....
...b ....
  |
   +----- Enable NMI on low battery detection
   +----- Enable NMI on low battery detection
</pre>
</pre>

Latest revision as of 13:11, 22 August 2024

Interrupts

The WonderSwan features fourteen different interrupts:

  • CPU interrupts - six provided by the V30MZ CPU ($00-$05),
  • Hardware interrupts - eight provided by the SoC's hardware ($00-$07, or $08-$0F, or $10-$1F, or ... $F8-$FF - controlled by an offset V):
    • Level - will be constantly requested while enabled and the prerequisite condition is true,
    • Edge - will only be requested while enabled the moment the prerequisite condition becomes true.

Level interrupts will be immediately retriggered upon acknowledging unless they are disabled, or their prerequisite condition is cleared (for example, a byte is read from the UART). Edge interrupts are only triggered the moment they happen; acknowledging them is sufficient until the next time one is issued (for example, until the next vertical blank).

The user can additionally make use of all 256 available interrupt vectors in their own code.

List of WonderSwan interrupts
Source Type Index Description
CPU N/A $00 DIV or IDIV instruction divide error

(division by zero or result overflow)

$01 Single-step (T flag)
$02 NMI (non-maskable interrupt)
$03 INT 3 opcode
$04 INTO opcode (if V = 1)
$05 BOUND opcode (if index out of bounds)
Hardware Level V + 0 UART Send Ready
Edge V + 1 Key Pressed
Level V + 2 Cartridge IRQ
V + 3 UART Receive Ready
Edge V + 4 Display Interrupt Line Match
V + 5 Vertical Blank Timer
V + 6 Display Vertical Blank
V + 7 Horizontal Blank Timer

I/O ports

Interrupt Vector Offset ($B0 write)

7  bit  0
---- ----
VVVV V...
|||| |
++++-+---- Interrupt vector offset

Interrupt Vector Request ($B0 read)

7  bit  0
---- ----
vvvv vvvv
|||| ||||
++++-++++- Interrupt vector requested
           from the CPU.
  • Bits 7 .. 3 of this will always equal the user-provided vector offset.
  • Bits 2 .. 0 of this will always equal the highest set bit index of Interrupt Status; if all bits in Interrupt Status are clear, they will equal 0.

Interrupt Enable ($B2)

7  bit  0
---- ----
iiii iiii
|||| ||||
++++-++++- Hardware interrupt to enable
           (acts as a mask)

Contrary to other systems, this also controls whether interrupts set the relevant bit in Interrupt Status.

Interrupt Status ($B4 read)

7  bit  0
---- ----
iiii iiii
|||| ||||
++++-++++- 1 if interrupt requested

Interrupt Acknowledge ($B6 write)

7  bit  0
---- ----
iiii iiii
|||| ||||
++++-++++- Write 1 to clear interrupt request

Interrupt NMI Control ($B7)

7  bit  0
---- ----
...b ....
   |
   +----- Enable NMI on low battery detection
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