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Add apple text functions and refactor draw logic for text

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This commit is contained in:
Peter Evans 2018-01-24 16:11:08 -06:00
parent 8bbe337643
commit d581194bbc
5 changed files with 123 additions and 79 deletions
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1
include/apple2.draw.h
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@ -5,7 +5,6 @@
#include "vm_bits.h"
extern void apple2_draw_pixel(apple2 *, vm_16bit);
extern void apple2_draw_text(apple2 *, vm_16bit);
extern void apple2_draw_40col(apple2 *);
#endif

11
include/apple2.text.h Normal file
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@ -0,0 +1,11 @@
#ifndef _APPLE2_TEXT_H_
#define _APPLE2_TEXT_H_
#include "apple2.h"
#include "vm_bitfont.h"
#include "vm_bits.h"
extern void apple2_text_draw(apple2 *, size_t);
extern int apple2_text_area(vm_area *, vm_bitfont *, size_t);
#endif

1
sources.cmake
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@ -7,6 +7,7 @@ set(erc_sources
apple2.kb.c
apple2.mem.c
apple2.pc.c
apple2.text.c
log.c
mos6502.c
mos6502.addr.c

80
src/apple2.draw.c
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@ -3,6 +3,7 @@
*/
#include "apple2.h"
#include "apple2.text.h"
/*
* These are the color codes for the lo-res colors that are available.
@ -82,83 +83,6 @@ apple2_draw_pixel_lores(apple2 *mach, vm_16bit addr)
vm_screen_draw_rect(mach->screen, &loc);
}
/*
* Draw the character indicated by the given address.
*/
void
apple2_draw_text(apple2 *mach, vm_16bit addr)
{
vm_8bit lsb, ch;
vm_16bit page_base;
vm_area dest;
// The text display buffers are located at "Page 1" and "Page 2",
// which are at byte 1024-2047 (0x0400-0x07FF) and byte 2048-3071
// (0x0800-0x0BFF) respectively. If the given address is not in
// those (contiguous) ranges, then let's bail.
if (addr < 0x0400 || addr > 0x0BFF) {
return;
}
// If we're updating a page 2 address and we're not in some kind of
// double resolution mode, then we shouldn't actually render the
// thing.
if (addr > 0x07FF && !apple2_is_double_video(mach)) {
return;
}
// In a given page for 40-column mode, you get 960 grid parts that
// you may use. In 80-column mode, it's more like 1920 grid parts
// (40x24 = 960, 80x24 = 1920). The way we look at this is the
// address indicates the place on the grid where text should go. We
// don't care how it got there. Let's figure out that position
// on-screen.
lsb = addr & 0xff; // column
// Regardless of which page we're rendering into, we can only use 40
// cells on the grid (that is, 0-39 from whatever value the msb is).
// It's possible to have an lsb greater than that, but if so, it's
// not anything we can render to the screen.
if (lsb > 39) {
return;
}
if ((addr & 0xff80) % 128 != 0) {
return;
}
// By default, we assume we're in text page 1. If the address ends
// up being greater than 0x07FF, then we must be in page 2.
page_base = 0x0400;
if (addr > 0x07FF) {
page_base = 0x0800;
}
// The absolute column position will be the font width times the
// lsb.
dest.xoff = lsb * mach->sysfont->width;
// The absolute row position will be the font height times the msb
// minus the page base (because the height is the same regardless of
// what page we're in). So if we're msb $0400, then we're starting
// on pixel row 0; but if we're msb $0480, then we are starting on
// pixel row 8 (where the font height is 8); etc.
dest.yoff = ((addr & 0xff80) - page_base) * mach->sysfont->height;
// Our width and height must be that of the font.
dest.width = mach->sysfont->width;
dest.height = mach->sysfont->height;
// And...lastly...what's in the address?
ch = mos6502_get(mach->cpu, addr);
// Let's firstly blank out that space on screen.
vm_bitfont_render(mach->sysfont, mach->screen, &dest, ' ');
// Now show the goddamned thing
vm_bitfont_render(mach->sysfont, mach->screen, &dest, ch);
}
void
apple2_draw_40col(apple2 *mach)
{
@ -169,6 +93,6 @@ apple2_draw_40col(apple2 *mach)
addr += 0x40;
}
apple2_draw_text(mach, addr);
apple2_text_draw(mach, addr);
}
}

109
src/apple2.text.c Normal file
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@ -0,0 +1,109 @@
/*
* apple2.text.c
*
* This code sits as a kind of wrapper over the bitmap fonts that the
* Apple II uses. Neither the system nor inverted fonts are exactly
* composed in the type of character set that Apple expects; they
* implement the glpyhs we need in order to make such. You can have
* inversed characters in the primary character set, for one; in the
* alternate character set, you can have MouseText glyphs, yet they are
* implemented as part of both fonts.
*/
#include "apple2.text.h"
void
apple2_text_draw(apple2 *mach, size_t addr)
{
int err;
vm_8bit ch;
vm_area dest;
vm_bitfont *font;
// If we're updating a page 2 address and we're not in some kind of
// double resolution mode, then we shouldn't actually render the
// thing.
if (addr > 0x07FF && !apple2_is_double_video(mach)) {
return;
}
// Default
font = mach->sysfont;
err = apple2_text_area(&dest, font, addr);
if (err != OK) {
return;
}
// What are we working with?
ch = mos6502_get(mach->cpu, addr);
// We treat special characters as spaces for display purposes.
if (ch < 0x20) {
vm_bitfont_render(font, mach->screen, &dest, ' ');
return;
}
// Blank out the space on the screen, then show the character
vm_bitfont_render(font, mach->screen, &dest, ' ');
vm_bitfont_render(font, mach->screen, &dest, ch);
}
int
apple2_text_area(vm_area *area, vm_bitfont *font, size_t addr)
{
vm_8bit lsb;
int page_base;
// The text display buffers are located at "Page 1" and "Page 2",
// which are at byte 1024-2047 (0x0400-0x07FF) and byte 2048-3071
// (0x0800-0x0BFF) respectively. If the given address is not in
// those (contiguous) ranges, then let's bail.
if (addr < 0x0400 || addr > 0x0BFF) {
return 0;
}
// In a given page for 40-column mode, you get 960 grid parts that
// you may use. In 80-column mode, it's more like 1920 grid parts
// (40x24 = 960, 80x24 = 1920). The way we look at this is the
// address indicates the place on the grid where text should go. We
// don't care how it got there. Let's figure out that position
// on-screen.
lsb = addr & 0xff; // column
// Regardless of which page we're rendering into, we can only use 40
// cells on the grid (that is, 0-39 from whatever value the msb is).
// It's possible to have an lsb greater than that, but if so, it's
// not anything we can render to the screen.
if (lsb > 0x39) {
return 0;
}
if ((addr & 0xff80) % 128 != 0) {
return 0;
}
// By default, we assume we're in text page 1. If the address ends
// up being greater than 0x07FF, then we must be in page 2.
page_base = 0x0400;
if (addr > 0x07FF) {
page_base = 0x0800;
}
// The absolute column position will be the font width times the
// lsb.
area->xoff = lsb * font->width;
// The absolute row position will be the font height times the msb
// minus the page base (because the height is the same regardless of
// what page we're in). So if we're msb $0400, then we're starting
// on pixel row 0; but if we're msb $0480, then we are starting on
// pixel row 8 (where the font height is 8); etc.
area->yoff = ((addr & 0xff80) - page_base) * font->height;
// Our width and height must be that of the font.
area->width = font->width;
area->height = font->height;
return OK;
}