RFC: Support arbitrary Cursor Positioning on VGA console?

[netzerohero]

VGA (ver-0.6) console supports ansi colors (select-graphic-rendition SGR) and cursor forward and backward (CUF and CUB).

Consider similar support for arbitrary Cursor Positioning (via ANSI escape codes).
Cursor Position == (ESC [ n ; m H) == CUP == Moves the cursor to row n, column m.

This could provide additional capability for the VGA-console; e.g., eventual support within C- and BASIC- environments in a user-friendly way.

For example (in BASIC dialects): VTAB n : HTAB m (Applesoft) or LOCATE n,m (GW-BASIC). The same feature would also be available in C via existing stdio printf(). This would open-up additional support to heritage BASIC code-bases and allow a c-programmer to use higher-level ansi standard stdio printfs without using lower-level calls to the VGA-graphics-pico directly (xreg calls).

[netzerohero]

Analysis:
Two approaches appear reasonable within rp6502 firmware:

1. Expand the Console-Canvas-Type to be similar to the Text-Canvas-Type in having a similar Text-Config-Structure containing a cursor x,y position. Given static-scoping limits of the term_state structures, accessor-functions could then provide x,y cursor positions, since direct xreg access is not available.

2. Expand function rp6502:src/vga/term/term.c :: term_out_state_CSI() to handle expanded CSI ansi-terminal-standard cases, including CUP - Cursor Position, and perhaps additional ansi=control-sequences as well (shown in yellow):
   

• Option-2 has the advantage of being "a standard driven" approach.
• Option-1 has the advantage of "growing into a solution" in that it aligns nicely to the existing Text-Canvas-Type (from C) and should low-level xreg access become available from EhBASIC.

[rumbledethumps]

If you want a mode 1 terminal emulator, write it on the 6502 side.

Adding mode 0 ANSI sequences has been low priority because there hasn't been a need. There's also a feature hold until picocomputer/rp6502#51 gets fixed.

[netzerohero]

Ah, thanks for the insights. For now I'm using minicom on the linux side.

[rumbledethumps]

Here's the supported ANSI sequences.
https://picocomputer.github.io/vga.html#terminal