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Today change make use of the Cursor module that we have created a while ago. The character buffer also being changed a bit
to make it easier to get and set characters based on the cursor location.
From now, the screen buffer will be pre-allocated with each W*H blocks. If there are more space needed, a new W*H block
will be allocated. Since the buffer can be huge, we use a variable called START_LINE to determine the render window of the
terminal. Everything in the range of [START_LINE..START_LINE + TERMINAL_ROWS] will be rendered.
┌ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ┐
Pre-Allocated
│ │
│ │
START_LINE ──▶ ┏━╋━━━━━━━━━━━━━━━━━━━━━━━┓ │
┃ ┃
┃ └ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ╋ ┘
┃ ┌ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ╋ ┐
┃ ┃
┃ │ Cursor ┃ │
┃ ┌┐ ┃
┃ │ └┘ ┃ │
┗━━━━━━━━━━━━━━━━━━━━━━━━━┛
│ │
└ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ┘
┌ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ┐
Allocate as
│ needed │
│ │
│ │
└ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ┘
Automatially scrolling will be handled by adjusting START_LINE based on its distance to the Cursor location.
With this change, we can now render the cursor correctly, some special chars’s behaviorp like \n or \r, or CSI sequences likeESC[H, ESC[K, ESC[5A,… can now be implemented.