From 636896a7fd68266397457db94d26313e4aca4adc Mon Sep 17 00:00:00 2001
From: D4VID <d4vid@d4vid.xyz>
Date: Sat, 21 Jun 2025 20:57:14 +0200
Subject: [PATCH] Modded text display

---
 lwcpu/.cargo/config.toml    |  8 ++++
 lwcpu/.vscode/settings.json |  5 +++
 lwcpu/src/lib.rs            | 77 +++++++++++++++++++++++++++++++++++++
 test/src/main.rs            | 14 ++++++-
 4 files changed, 103 insertions(+), 1 deletion(-)
 create mode 100644 lwcpu/.cargo/config.toml
 create mode 100644 lwcpu/.vscode/settings.json

diff --git a/lwcpu/.cargo/config.toml b/lwcpu/.cargo/config.toml
new file mode 100644
index 0000000..6dfb735
--- /dev/null
+++ b/lwcpu/.cargo/config.toml
@@ -0,0 +1,8 @@
+[build]
+target = "riscv32i-unknown-none-elf"
+
+[target.riscv32i-unknown-none-elf]
+rustflags = [
+  "-C", "link-arg=-Tmemory.x",
+  "-C", "link-arg=-Tlink.x",
+]
diff --git a/lwcpu/.vscode/settings.json b/lwcpu/.vscode/settings.json
new file mode 100644
index 0000000..1f30ed8
--- /dev/null
+++ b/lwcpu/.vscode/settings.json
@@ -0,0 +1,5 @@
+{
+    "rust-analyzer.check.allTargets": false,
+    "rust-analyzer.cargo.allTargets": false,
+    "rust-analyzer.cargo.target": "riscv32i-unknown-none-elf"
+}
diff --git a/lwcpu/src/lib.rs b/lwcpu/src/lib.rs
index 9a97b27..d220a87 100644
--- a/lwcpu/src/lib.rs
+++ b/lwcpu/src/lib.rs
@@ -11,6 +11,7 @@ pub const KEYBOARD_OFFSET        : u32 = 0x10;
 pub const CHAR_CONTROL_OFFSET    : u32 = 0x20;
 pub const SCREEN_CONTROL_OFFSET  : u32 = 0x22;
 pub const CHAR_DISPLAY_OFFSET    : u32 = 0x24;
+pub const TEXT_DISPLAY_OFFSET    : u32 = 0x28; // cheeseutil modded display 64x64 characters
 pub const AUDIO_MAIN_OFFSET      : u32 = 0x30;
 pub const SCREEN_OFFSET          : u32 = 0x80;
 
@@ -21,6 +22,7 @@ pub const CHAR_DISPLAY_POINTER   : *mut u8  = (BASE_POINTER + CHAR_DISPLAY_OFFSE
 pub const KEYBOARD_POINTER       : *mut u32 = (BASE_POINTER + KEYBOARD_OFFSET)       as *mut u32;
 pub const SCREEN_CONTROL_POINTER : *mut u16 = (BASE_POINTER + SCREEN_CONTROL_OFFSET) as *mut u16;
 pub const CHAR_CONTROL_POINTER   : *mut u16 = (BASE_POINTER + CHAR_CONTROL_OFFSET)   as *mut u16;
+pub const TEXT_DISPLAY_POINTER   : *mut u8  = (BASE_POINTER + TEXT_DISPLAY_OFFSET)   as *mut u8;
 pub const AUDIO_MAIN_POINTER     : *mut u32 = (BASE_POINTER + AUDIO_MAIN_OFFSET)     as *mut u32;
 pub const SCREEN_POINTER         : *mut u32 = (BASE_POINTER + SCREEN_OFFSET)         as *mut u32;
 
@@ -141,6 +143,81 @@ impl core::fmt::Write for CharDisplay {
     }
 }
 
+pub struct TextDisplay {
+    pos: u16
+}
+impl TextDisplay {
+    const CLEAR        : u8 = 0b00000001;
+    const SET_CHAR     : u8 = 0b00000010;
+    const SET_CURSOR   : u8 = 0b00000100;
+    const BLINK        : u8 = 0b00001000;
+    const SCROLL_UP    : u8 = 0b00010000;
+    // const SCROLL_DOWN  : u8 = 0b00100000;
+    // const SCROLL_LEFT  : u8 = 0b01000000;
+    // const SCROLL_RIGHT : u8 = 0b10000000;
+
+    #[inline]
+    pub fn init(&mut self, blink: bool) {
+        unsafe {
+            let control_ptr = TEXT_DISPLAY_POINTER.offset(3);
+            write_volatile(control_ptr, Self::CLEAR);
+            match blink {
+                true => {
+                    write_volatile(control_ptr, Self::BLINK);
+                },
+                false => {
+                    write_volatile(control_ptr, 0);
+                },
+            }
+        }
+    }
+    #[inline]
+    pub fn put_char(&mut self, ch: u8) {
+        unsafe {
+            let control_ptr = TEXT_DISPLAY_POINTER.offset(3);
+            let control = read_volatile(control_ptr);
+
+            if ch == b'\n' {
+                if self.pos >= 63*64 { // last row
+                    write_volatile(control_ptr, Self::SCROLL_UP);
+                    write_volatile(control_ptr, control);
+                } else {
+                    self.pos += 64; // increment row
+                }
+                self.pos &= !63u16; // set column to 0
+                return;
+            }
+
+            write_volatile(TEXT_DISPLAY_POINTER as *mut u16, self.pos);
+            write_volatile(TEXT_DISPLAY_POINTER.offset(2), ch);
+            write_volatile(control_ptr, Self::SET_CHAR);
+            write_volatile(control_ptr, control);
+
+            self.pos += 1;
+
+            write_volatile(TEXT_DISPLAY_POINTER as *mut u16, self.pos);
+
+            write_volatile(control_ptr, Self::SET_CURSOR);
+            write_volatile(control_ptr, control);
+        }
+    }
+}
+impl Default for TextDisplay {
+    #[inline]
+    fn default() -> Self {
+        Self { pos: 0 }
+    }
+}
+impl core::fmt::Write for TextDisplay {
+    #[inline]
+    fn write_str(&mut self, s: &str) -> core::fmt::Result {
+        for ch in s.bytes() {
+            self.put_char(ch);
+        }
+        return Ok(());
+    }
+}
+
 pub struct NumberDisplay {}
 impl NumberDisplay {
     #[inline]
diff --git a/test/src/main.rs b/test/src/main.rs
index e047f3e..ecc4dd0 100644
--- a/test/src/main.rs
+++ b/test/src/main.rs
@@ -2,7 +2,7 @@
 #![no_main]
 
 use core::{fmt::Write, panic::PanicInfo, ptr::{read_volatile, write_volatile}};
-use lwcpu::{NumberDisplay, Screen, ScreenMode, CharDisplay, SCREEN_POINTER};
+use lwcpu::{CharDisplay, NumberDisplay, Screen, ScreenMode, TextDisplay, SCREEN_POINTER};
 use riscv_rt::entry;
 
 #[panic_handler]
@@ -16,8 +16,20 @@ fn panic_handler(_info: &PanicInfo) -> ! {
 
 const HELLO_WORLD: &str = " Hello world!";
 
+#[inline(never)]
+fn test_text_display() {
+    let mut text = TextDisplay::default();
+    text.init(true);
+    text.write_str("Lmao yeet\nlook at this!\nI have a text display I can type into.\nSo cool!!!").ok();
+    for _ in 0..100 {
+        text.write_str("aaa\n").ok();
+    }
+}
+
 #[entry]
 fn main() -> ! {
+    test_text_display();
+
     NumberDisplay::display_number(0);
     Screen::init(ScreenMode::Buffered);
     let mut text = CharDisplay{};