3Dfx framebuffer driver tdfxfb_cursor() bit-wise ANDing

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Date:	Thu, 30 Oct 2003 20:58:49 -0800 (PST)
To: linux-kernel maillist <linux-kernel@vger.kernel.org>, hmallat@cc.hut.fi

Following is the code section from
 linux-2.6.0-test9\drivers\video\tdfxfb.c

This is the 3Dfx framebuffer driver.

I have noticed that if statements with bit-wise AND
(&) is been typed as logical AND (&&)
i.e. all the if statements anding with FB_CUR_*

as I don't have a 3Dfx card I am unable to test.
Sorry for not attaching a patch file.

---code section---

static int tdfxfb_cursor(struct fb_info *info, struct
fb_cursor *cursor)
{
        struct tdfx_par *par = (struct tdfx_par *) info->par;
        unsigned long flags;

        /*
         * If the cursor is not be changed this means either
we want the
         * current cursor state (if enable is set) or we want
to query what
         * we can do with the cursor (if enable is not set)
          */
        if (!cursor->set) return 0;

        /* Too large of a cursor :-( */
        if (cursor->image.width > 64 || cursor->image.height
> 64)
                return -ENXIO;

        /*
         * If we are going to be changing things we should
disable
         * the cursor first
         */
        if (info->cursor.enable) {
                spin_lock_irqsave(&par->DAClock, flags);
                info->cursor.enable = 0;
                del_timer(&(par->hwcursor.timer));
                tdfx_outl(par, VIDPROCCFG, par->hwcursor.disable);
                spin_unlock_irqrestore(&par->DAClock, flags);
        }

        /* Disable the Cursor */
        if ((cursor->set && FB_CUR_SETCUR) &&
!cursor->enable)
                return 0;

        /* fix cursor color - XFree86 forgets to restore it
properly */
        if (cursor->set && FB_CUR_SETCMAP) {
                struct fb_cmap cmap = cursor->image.cmap;
                unsigned long bg_color, fg_color;

                cmap.len = 2;/* Voodoo 3+ only support 2 color
cursors*/
                fg_color = ((cmap.red[cmap.start] << 16) |
                            (cmap.green[cmap.start] << 8) |
                            (cmap.blue[cmap.start]));
                bg_color = ((cmap.red[cmap.start+1] << 16) |
                            (cmap.green[cmap.start+1] << 8) |
                            (cmap.blue[cmap.start+1]));
                fb_copy_cmap(&cmap, &info->cursor.image.cmap, 0);
                spin_lock_irqsave(&par->DAClock, flags);
                banshee_make_room(par, 2);
                tdfx_outl(par, HWCURC0, bg_color);
                tdfx_outl(par, HWCURC1, fg_color);
                spin_unlock_irqrestore(&par->DAClock, flags);
        }

        if (cursor->set && FB_CUR_SETPOS) {
                int x, y;

                x = cursor->image.dx;
                y = cursor->image.dy;
                y -= info->var.yoffset;
                info->cursor.image.dx = x;
                info->cursor.image.dy = y;
                x += 63;
                y += 63;
                spin_lock_irqsave(&par->DAClock, flags);
                banshee_make_room(par, 1);
                tdfx_outl(par, HWCURLOC, (y << 16) + x);
                spin_unlock_irqrestore(&par->DAClock, flags);
        }

        /* Not supported so we fake it */
        if (cursor->set && FB_CUR_SETHOT) {
                info->cursor.hot.x = cursor->hot.x;
                info->cursor.hot.y = cursor->hot.y;
        }

        if (cursor->set && FB_CUR_SETSHAPE) {
                /*
                  * Voodoo 3 and above cards use 2 monochrome cursor
patterns.
                 * The reason is so the card can fetch 8 words at
a time
                 * and are stored on chip for use for the next 8
scanlines.
                 * This reduces the number of times for access to
draw the
                 * cursor for each screen refresh.
                 * Each pattern is a bitmap of 64 bit wide and 64
bit high
                 * (total of 8192 bits or 1024 Kbytes). The two
patterns are
                 * stored in such a way that pattern 0 always
resides in the
                 * lower half (least significant 64 bits) of a 128
bit word
                 * and pattern 1 the upper half. If you examine the
data of
                 * the cursor image the graphics card uses then from
the
                 * begining you see line one of pattern 0, line one
of
                 * pattern 1, line two of pattern 0, line two of
pattern 1,
                 * etc etc. The linear stride for the cursor is
always 16 bytes
                 * (128 bits) which is the maximum cursor width
times two for
                 * the two monochrome patterns.
                 */
                u8 *cursorbase = (u8 *) info->cursor.image.data;
                char *bitmap = (char *)cursor->image.data;
                char *mask = cursor->mask;
                int i, j, k, h = 0;

                for (i = 0; i < 64; i++) {
                        if (i < cursor->image.height) {
                                j = (cursor->image.width + 7) >> 3;
                                k = 8 - j;

                                for (;j > 0; j--) {
                                /* Pattern 0. Copy the cursor bitmap to it */
                                        fb_writeb(*bitmap, cursorbase + h);
                                        bitmap++;
                                /* Pattern 1. Copy the cursor mask to it */
                                        fb_writeb(*mask, cursorbase + h + 8);
                                        mask++;
                                        h++;
                                }
                                for (;k > 0; k--) {
                                        fb_writeb(0, cursorbase + h);
                                        fb_writeb(~0, cursorbase + h + 8);
                                        h++;
                                }
                        } else {
                                fb_writel(0, cursorbase + h);
                                fb_writel(0, cursorbase + h + 4);
                                fb_writel(~0, cursorbase + h + 8);
                                fb_writel(~0, cursorbase + h + 12);
                                h += 16;
                        }
                }
        }
        /* Turn the cursor on */
        cursor->enable = 1;
        info->cursor = *cursor;
        mod_timer(&par->hwcursor.timer, jiffies+HZ/2);
        spin_lock_irqsave(&par->DAClock, flags);
        banshee_make_room(par, 1);
        tdfx_outl(par, VIDPROCCFG, par->hwcursor.enable);
        spin_unlock_irqrestore(&par->DAClock, flags);
        return 0;
}

Thanks,
Vinayak

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• Previous message: Junji Kanemaru: "patch: logips2pp.c - Wheel(middle) button fix"
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