libvterm

Make your terminal emulator colorful!

LibVTerm is an embeddable ANSI C89 (C90) library for parsing ANSI escape sequences.
It is constructed in such way it requires only ctype.h, string.h, stddef.h and at least a malloc-styled allocation API.

Getting started

The library should be capable of compiling on virtually any C89-compliant C compiler so the repo doesn't contain any build scripts - you do it yourself!
The way library communicates with the outer world is callbacks: libvterm has about 8 of them and 2 are required.

System requirements

1. A reliable void *malloc(size_t)-ish function (libvterm doesn't check for NULL pointers upon allocation).
2. A reliable void free(void *)-ish function.

Callback descriptions

1. mem_alloc - allocate a block of N bytes. Required.
2. mem_free - free a previously allocated block. Required.
3. misc_sequence - allows parsing custom escape sequences specific for certain implementations.
4. set_cursor - updates the cursor position.
5. mode_change - implementation-specific actions upon video mode changes.
6. draw_cell - put a single cell to the screen.
7. response - write a byte back as a terminal response.
8. ascii - handle miscellaneous ASCII escape characters.

Minimal example

This is taken from Demos (from about here)
The above source file doesn't exist anymore :)

Code

static void on_misc_sequence(
    const struct vterm *vt, int chr)
{
    /* TMVGA driver supports DEC VT-220 "show/hide cursor" private
     * sequences because VGA CRTC can show and hide the hardware cursor */
    /* Some x86 port i/o stuff is going on here... */
}

static void on_set_cursor(
    const struct vterm *vt,
    const struct vterm_cursor *cursor)
{
    /* Again, TMVGA supports moving the cursor because VGA CRTC
     * has hardware cursor support so we don't need to emulate it. */
    /* Some more x86 port i/o stuff is going on here... */
}

static void on_draw_cell(
    const struct vterm *vt, int chr,
    unsigned int x, unsigned int y,
    const struct vterm_attrib *attrib)
{
    /* The colors in VGA text mode slightly differ from the colors
     * defined by the ANSI standard so this function remaps the colors
     * depending on the flags (like INVERT or BRIGHT) and writes the
     * character directly to the video memory. It also would be worth
     * noting that not all attributes may be supported by the implementation
     * so you are free to check for whatever you want to check for here. */
    /* Some x86 and VGA trickery is going on here... */
}

static struct vterm vt = { 0 };

int init_tmvga(/* ... some bootloader stuff ... */)
{
    struct vterm_callbacks callbacks;
    /* some unrelated code */
    
    /* Here we send the required memory allocation functions
     * to the library. Without them vterm_init will fail. */
    callbacks.mem_alloc = &kmalloc;
    callbacks.mem_free = &kmfree;
    
    /* These are not required by the library but without, say
     * draw_cell callback we won't be able to see anything! */
    callbacks.misc_sequence = &on_misc_sequence;
    callbacks.set_cursor = &on_set_cursor;
    callbacks.draw_cell = &on_draw_cell;
    
    vterm_init(&vt, &callbacks, NULL);
    
    /* some unrelated code */
}

Action!