From d233d07ed28c9b56aaf377ca88573550f07dcc20 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jo=C3=A3o=20Magalh=C3=A3es?= <joamag@gmail.com>
Date: Sat, 2 Jul 2022 12:32:08 +0100
Subject: [PATCH] =?UTF-8?q?feat:=20initial=20boot=20loading=20support=20?=
=?UTF-8?q?=F0=9F=99=8C?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
---
src/mmu.rs | 16 +++++-----------
src/ppu.rs | 13 +++++++++----
2 files changed, 14 insertions(+), 15 deletions(-)
diff --git a/src/mmu.rs b/src/mmu.rs
index 8b333bd2..06a10491 100644
--- a/src/mmu.rs
+++ b/src/mmu.rs
@@ -49,22 +49,16 @@ impl Mmu {
}
// ROM0 (12 KB/16 KB)
0x1000 | 0x2000 | 0x3000 => self.rom[addr as usize],
- // ROM1 (unbanked) (16 KB)
+ // ROM1 (Unbanked) (16 KB)
0x4000 | 0x5000 | 0x6000 | 0x7000 => self.rom[addr as usize],
// Graphics: VRAM (8 KB)
- 0x8000 | 0x9000 => {
- self.ppu.vram[(addr & 0x1fff) as usize]
- }
+ 0x8000 | 0x9000 => self.ppu.vram[(addr & 0x1fff) as usize],
// External RAM (8 KB)
- 0xa000 | 0xb000 => {
- self.eram[(addr & 0x1fff) as usize]
- }
+ 0xa000 | 0xb000 => self.eram[(addr & 0x1fff) as usize],
// Working RAM (8 KB)
0xc000 | 0xd000 => self.ram[(addr & 0x1fff) as usize],
// Working RAM Shadow
- 0xe000 => {
- self.ram[(addr & 0x1fff) as usize]
- }
+ 0xe000 => self.ram[(addr & 0x1fff) as usize],
// Working RAM Shadow, I/O, Zero-page RAM
0xf000 => match addr & 0x0f00 {
0x000 | 0x100 | 0x200 | 0x300 | 0x400 | 0x500 | 0x600 | 0x700 | 0x800 | 0x900
@@ -102,7 +96,7 @@ impl Mmu {
0x1000 | 0x2000 | 0x3000 => {
println!("WRITING TO ROM 0");
}
- // ROM1 (unbanked) (16 KB)
+ // ROM1 (Unbanked) (16 KB)
0x4000 | 0x5000 | 0x6000 | 0x7000 => {
println!("WRITING TO ROM 1");
}
diff --git a/src/ppu.rs b/src/ppu.rs
index a26556cd..07e1aae1 100644
--- a/src/ppu.rs
+++ b/src/ppu.rs
@@ -218,11 +218,16 @@ impl Ppu {
}
fn render_line(&mut self) {
+ // obtains the base address of the background map using the bg map flag
+ // that control which background map is going to be used
let mut map_offset: usize = if self.bg_map { 0x1c00 } else { 0x1800 };
- map_offset += (((self.line + self.scy) & 0xff) >> 3) as usize;
+
+ // increments the offset by the number of lines and the SCY (scroll Y)
+ // divided by 8 (as the tiles are 8x8 pixels)
+ map_offset += ((((self.line + self.scy) & 0xff) >> 3) as usize) * 32;
// calculates the sprite line offset by using the SCX register
- // shifted by 3 meaning as the tiles are 8x8
+ // shifted by 3 meaning that the tiles are 8x8
let mut line_offset: usize = (self.scx >> 3) as usize;
// calculates both the current Y and X positions within the tiles
@@ -233,7 +238,7 @@ impl Ppu {
// if the tile data set in use is #1, the indices are
// signed, then calculates a real tile offset
let mut tile_index = self.vram[map_offset + line_offset] as usize;
- if self.bg_tile && tile_index < 128 {
+ if !self.bg_tile && tile_index < 128 {
tile_index += 256;
}
@@ -273,7 +278,7 @@ impl Ppu {
// calculates the tile index nad makes sure the value
// takes into consideration the bg tile value
tile_index = self.vram[map_offset + line_offset] as usize;
- if self.bg_tile && tile_index < 128 {
+ if !self.bg_tile && tile_index < 128 {
tile_index += 256;
}
}
--
GitLab