On CG50 gint utilizes a triple-buffer mechanism to speed up rendering by DMA transfering one of the back buffers to display while allowing client code to write to the other at the same time. Except being swapped in and out between the two, they are apparently independ to each other, eg. there is no pixel copy when `dupdate()`. This is suitable for frame based applications like games.

In one of my add-ins I simply disabled triple-buffering (to save one `memcpy()` call), but the calc would reboot in a few seconds each time when the add-in was launched.

Anyone ever encountered the same problem please advise?

Here is the relevant

static void print(const char *buf, int len) {
#define LINE_HEIGHT     16

    static struct {
        bool init;
        int x, y;
    } a = { .init = false, };

    if (!a.init) {
        a.init = true;
        a.x = 0;
        a.y = LINE_HEIGHT;

        // Disable triple buffer
        uint16_t *vram1, *vram2;
        dgetvram(&vram1, &vram2);
        dsetvram(vram1, NULL);


    int x1 = a.x;
    int y1 = a.y;

    int len1 = 0;
    while (len1 < len) {
        int w;
        dnsize(buf + len1, 1, NULL, &w, NULL);

        int max_w = DWIDTH - x1;
        if (w > max_w) {
            x1 = 0;
            y1 += LINE_HEIGHT;
            if (y1 >= DHEIGHT) {
                y1 = LINE_HEIGHT;

        dtext_opt(x1, y1, C_BLACK, C_NONE, DTEXT_LEFT, DTEXT_BOTTOM, buf + len1, 1);
        x1 += w;
    } // while


    a.x = x1;
    a.y = y1;


I noticed recently that despite what's being advertised in the prototype, you need to set both pointers for it to works:

dsetvram(vram1, vram1);

I am planning to make double-buffering back the default in the next version. This is because, while it was believed years ago that the performance boost from triple buffering could be reaped "transparently" just by running C code, performance testing in various add-ins since have shown that this is far from the case, and the boost that you get is debatable at best.
Lephe wrote:

dsetvram(vram1, vram1);

This does the trick. Thanks! Good Idea
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