Common errors

"File not found"

The path is wrong. Two things to watch:

• The workspace root is ~, e.g. ~/examples/c/app/tetris.c
• After cd on the Shell page, a relative path is relative to the current directory

"Label not found: xxx"

The linker cannot find that function. Common causes:

1. The function is not in the standard library - see the interface list under "UI development"
2. A typo in the function name
3. The function is declared after it is called (missing forward declaration)

"Memory error (PC=...)" plus a pile of registers

The program ran off the rails: it touched memory it should not have touched. Check in this order:

1. Array out of bounds (the most common by far) - check the index range
2. A pointer or address computed wrong
3. The wrong number of arguments to a function (too many or too few both misalign the stack)

In the report, PC=00000047 is the address of the instruction that faulted; the line below it, MOVE R0, @1 ..., is the instruction that faulted, and something like address=FFFFFFFC is the address it touched.

"Compilation timed out"

The program is too large, or the compiler got stuck in its own code. See the watchdog note in "Build and run".

The program runs but the window is black

• ui_2d_present() is missing - every frame has to be committed once
• Or the program exited right after opening the window, before drawing its first frame: draw the first frame immediately after ui_win_open
• Check whether the color passed to ui_2d_clear() is fully transparent (an alpha of 0, as in 0x00......)

Touch does nothing

• Coordinates are canvas coordinates, not screen coordinates (the canvas is centered with its aspect ratio kept, so there can be black bars)
• A tap that lands on a black bar is dropped (that is intentional)
• Check whether ui_msg_clear() was called to drop what was left over from the previous round

Still not right

1. Run vml test first to confirm the environment is healthy
2. Shrink the program to the smallest case (keep only the lines that misbehave) and run it again
3. Ask the AI: "look at examples/c/xxx.c and tell me why it reports a memory error"