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add docs for debug output

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Dennis Ranke
2022-05-08 19:47:07 +02:00
parent 8e9bb002bc
commit 599873890a
6 changed files with 44 additions and 27 deletions
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site/content/docs.md
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@@ -225,30 +225,45 @@ Moving/printing past any border does not cause any special operation, the cursor
Characters 0-31 are control characters and don't print by default. They take the next 0-2 following characters as parameters.
Avoid the reserved control chars, they are currently NOPs but their behavior can change in later MicroW8 versions.
| Code | Parameters | Operation |
| ----- | ---------- | ------------------------------------ |
| 0 | - | Nop |
| 1 | char | Print char (including control chars) |
| 2-3 | - | Reserved |
| 4 | - | Switch to normal mode |
| 5 | - | Switch to graphics mode |
| 6 | - | Reserved |
| 7 | - | Bell / trigger sound channel 0 |
| 8 | - | Move cursor left |
| 9 | - | Move cursor right |
| 10 | - | Move cursor down |
| 11 | - | Move cursor up |
| 12 | - | do `cls(background_color)` |
| 13 | - | Move cursor to the left border |
| 14 | color | Set the background color |
| 15 | color | Set the text color |
| 16-23 | - | Reserved |
| 24 | - | Swap text/background colors |
| 25-30 | - | Reserved |
| 31 | x, y | Set cursor position (*) |
| Code | Parameters | Operation |
| ----- | ---------- | ------------------------------------------ |
| 0 | - | Nop |
| 1 | char | Print char (including control chars) |
| 2-3 | - | Reserved |
| 4 | - | Switch to normal mode, reset cursor to 0,0 |
| 5 | - | Switch to graphics mode |
| 6 | - | Switch output to (debug) console |
| 7 | - | Bell / trigger sound channel 0 |
| 8 | - | Move cursor left |
| 9 | - | Move cursor right |
| 10 | - | Move cursor down |
| 11 | - | Move cursor up |
| 12 | - | do `cls(background_color)` |
| 13 | - | Move cursor to the left border |
| 14 | color | Set the background color |
| 15 | color | Set the text color |
| 16-23 | - | Reserved |
| 24 | - | Swap text/background colors |
| 25-30 | - | Reserved |
| 31 | x, y | Set cursor position (*) |
(*) In graphics mode, the x coordinate is doubled when using control char 31 to be able to cover the whole screen with one byte.
#### Debug output
Control code 6 switches all text output (except codes 4 and 5 to switch output back to the screen) to the console. Where exactly this ends
up (if at all) is an implementation detail of the runtimes. The native dev-runtime writes the debug output to `stdout`, the web runtime to
the debug console using `console.log`. Both implementation buffer the output until they encounter a newline character (10) in the output stream.
There may be future runtimes that ignore the debug output completely.
In CurlyWas, a simple way to log some value might look like this:
```
printChar('\06V: '); // switch to console out, print some prefix
printInt(some_value);
printChar('\n\4'); // newline and switch back to screen
```
### fn printChar(char: i32)
Prints the character in the lower 8 bits of `char`. If the upper 24 bits are non-zero, right-shifts `char` by 8 bits and loops back to the beginning.