 @@ -1,14 +1,14 @@
-/*	$NetBSD: topcat.c,v 1.11 2024/05/01 19:28:33 tsutsui Exp $	*/
+/*	$NetBSD: topcat.c,v 1.12 2024/05/04 16:06:57 tsutsui Exp $	*/
 /*	$OpenBSD: topcat.c,v 1.15 2006/08/11 18:33:13 miod Exp $	*/
 /*
  * Copyright (c) 2005, Miodrag Vallat.
  * All rights reserved.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
 @@ -341,31 +341,44 @@ topcat_reset(struct diofb *fb, int scode
 		fb->planemask = *fbp;
 		*fbp = save;
 		for (fb->planes = 1; fb->planemask >= (1 << fb->planes);
 		    fb->planes++);
 		if (fb->planes > 8)
 			fb->planes = 8;
 		fb->planemask = (1 << fb->planes) - 1;
+	}
 	/*
 	 * Some displays, such as the HP332 and HP340 internal video
 	 * and HP98542/98543 appear to return a display width of 1024
-	 * instead of 512.
+	 * instead of 512. It looks these boards have actually have
 	 * enough 64KB (1bpp) or 256KB (4bpp) VRAM and RAMDAC capabilities
 	 * to display 1024x400 pixels.
+	 *
-	 * It looks these boards have VRAM with sparse address layout,
+	 * However HP's officlal "Service Information Manual" for
-	 * i.e. 1 bit or 4 bits per pixel but 2 bytes per pixel, so
+	 * "HP 900 Series 300 Computers Models 330/350" says:
-	 * we have to handle 512 pixels per line with 1024 bytes per line.
+	 *  "The medium-resolution board uses eight memory chips per plane.
 	 *   This is enough to display 512 doubled pixels by 400 scan lines."
+	 *
 	 * This "512 doubled pixels" implies that the native HP-UX treated
 	 * these 1024x400 framebuffers as pseudo 512x400 ones because
 	 * ancient 1980s CRTs (such as 35741) didn't display such higher
 	 * resolution. Furthermore, even modern LCDs can only handle
 	 * upto 720 pixels in the "400 line" as VGA compatible mode.
+	 *
 	 * As mentioned above, we treat these 1024x400 1 bit or 4 bit
 	 * framebuffers as "2 bytes per pixel" ones, so we have to handle
 	 * 512 pixels per line with 1024 bytes per line.
 	 */
 	if (fb->planes <= 4 && fb->dwidth == 1024 && fb->dheight == 400) {
 		fb->dwidth = 512;
 		sparse = true;
+	}
 	fb->bmv = topcat_windowmove;
 	topcat_restore(fb);
 	diofb_fbsetup(fb);
 	if (!sparse) {
 		/* save original rasops putchar op */
 		fb->wsputchar = ri->ri_ops.putchar;
 		ri->ri_ops.putchar = topcat_putchar8;
 @@ -570,27 +583,28 @@ topcat_putchar8(void *cookie, int row, i
+{
 	struct rasops_info *ri = (struct rasops_info *)cookie;
 	struct diofb *diofb = ri->ri_hw;
 	volatile struct tcboxfb *tc = (struct tcboxfb *)diofb->regkva;
 	/* Wait windowmove ops complete before drawing a glyph */
 	tc_waitbusy(tc, diofb->planemask);
 	/* Call the original rasops putchar */
 	(*diofb->wsputchar)(cookie, row, col, uc, attr);
+}
 /*
- * Put a single character on 1 bpp or 4 bpp variants with sparse VRAM addresses
+ * Put a single character on 1 bpp (98542) or 4 bpp (98543) variants
  * with 1024x400 VRAM to treat them as a pseudo 512x400 bitmap.
  */
 static void
 topcat_putchar1_4(void *cookie, int row, int col, u_int uc, long attr)
+{
 	int width, height, cnt, fs;
 	uint32_t fb;
 	uint8_t *fr, clr[2];
 	uint8_t *dp, *rp;
 	struct rasops_info *ri;
 	struct diofb *diofb;
 	volatile struct tcboxfb *tc;
 	ri = (struct rasops_info *)cookie;
 @@ -602,28 +616,28 @@ topcat_putchar1_4(void *cookie, int row,
 	    (col * ri->ri_xscale * 2);
 	height = ri->ri_font->fontheight;
 	width = ri->ri_font->fontwidth;
 	clr[0] = (uint8_t)ri->ri_devcmap[(attr >> 16) & 0xf];
 	clr[1] = (uint8_t)ri->ri_devcmap[(attr >> 24) & 0xf];
 	/* Wait windowmove ops complete before drawing a glyph */
 	diofb = ri->ri_hw;
 	tc = (struct tcboxfb *)diofb->regkva;
 	tc_waitbusy(tc, diofb->planemask);
 	/*
-	 * At least HP98543 requires to write 4 bpp data onto
+	 * We have to put pixel data to both odd and even addresses
-	 * both odd and even addresses.
+	 * to handle "doubled pixels" as noted above.
 	 */
 	if (uc == ' ') {
 		uint16_t c = clr[0];
 		c = c << 8 | c;
 		while (height--) {
 			dp = rp;
 			rp += ri->ri_stride;
 			for (cnt = width; cnt; cnt--) {
 				*(uint16_t *)dp = c;
 				dp += 2;
+			}