From: Akos Kiss <akiss@inf.u-szeged.hu>
Date: Mon, 5 Oct 2020 16:01:40 +0000 (+0200)
Subject: Fix the virtual memory of the HD44780 part
X-Git-Url: https://git.htl-mechatronik.at/public/?a=commitdiff_plain;h=cb6fcbead0826fdbe54dc0b2218eb77d229c8248;p=sx%2Fsimavr.git

Fix the virtual memory of the HD44780 part

In HD44780, the DDRAM has an address space of 0x80 bytes, while
CGRAM has 0x40 bytes. To ensure their proper separation, the vram
should have 0x80+0x40 bytes with the CGRAM starting at 0x80.
---

diff --git a/examples/parts/hd44780.c b/examples/parts/hd44780.c
index 144cbfc..84fb993 100644
--- a/examples/parts/hd44780.c
+++ b/examples/parts/hd44780.c
@@ -55,7 +55,7 @@ static void
 _hd44780_clear_screen(
 		hd44780_t *b)
 {
-	memset(b->vram, ' ', 80);
+	memset(b->vram, ' ', 0x80);
 	hd44780_set_flag(b, HD44780_FLAG_DIRTY, 1);
 	avr_raise_irq(b->irq + IRQ_HD44780_ADDR, b->cursor);
 }
@@ -84,14 +84,14 @@ hd44780_kick_cursor(
 	hd44780_t *b)
 {
 	if (hd44780_get_flag(b, HD44780_FLAG_I_D)) {
-		if (b->cursor < 79)
+		if (b->cursor < 0x80-1)
 			b->cursor++;
-		else if (b->cursor < 80+64-1)
+		else if (b->cursor < 0x80+0x40-1)
 			b->cursor++;
 	} else {
-		if (b->cursor < 80 && b->cursor)
+		if (b->cursor < 0x80 && b->cursor)
 			b->cursor--;
-		else if (b->cursor > 80)
+		else if (b->cursor > 0x80)
 			b->cursor--;
 		hd44780_set_flag(b, HD44780_FLAG_DIRTY, 1);
 		avr_raise_irq(b->irq + IRQ_HD44780_ADDR, b->cursor);
@@ -139,7 +139,7 @@ hd44780_write_command(
 			break;
 		// Set	CGRAM address
 		case 6:		// 0 1 ADD ADD ADD ADD ADD ADD ADD
-			b->cursor = 64 + (b->datapins & 0x3f);
+			b->cursor = 0x80 + (b->datapins & 0x3f);
 			break;
 		// Function	set
 		case 5:	{	// 0 0 1 DL N F x x
@@ -246,7 +246,7 @@ hd44780_process_read(
 			delay = 0;	// no raising busy when reading busy !
 
 			// low bits are the current cursor
-			b->readpins = b->cursor < 80 ? b->cursor : b->cursor-64;
+			b->readpins = b->cursor < 0x80 ? b->cursor : b->cursor-0x80;
 			int busy = hd44780_get_flag(b, HD44780_FLAG_BUSY);
 			b->readpins |= busy ? 0x80 : 0;
 
@@ -391,4 +391,3 @@ hd44780_init(
 	printf("LCD: %duS is %d cycles for your AVR\n",
 			1, (int)avr_usec_to_cycles(avr, 1));
 }
-
diff --git a/examples/parts/hd44780.h b/examples/parts/hd44780.h
index 39353e5..e359e6f 100644
--- a/examples/parts/hd44780.h
+++ b/examples/parts/hd44780.h
@@ -98,7 +98,7 @@ typedef struct hd44780_t
 	int		w, h;				// width and height of the LCD
 
 	uint16_t cursor;			// offset in vram
-	uint8_t  vram[80 + 64];
+	uint8_t  vram[0x80 + 0x40];
 
 	uint16_t pinstate;			// 'actual' LCd data pins (IRQ bit field)
 	// uint16_t oldstate;			/// previous pins
@@ -134,4 +134,4 @@ hd44780_get_flag(
 	return (b->flags &  (1 << bit)) != 0;
 }
 
-#endif 
+#endif