From 62ab718e4dd6094cd100c5a231b25c114e757a9c Mon Sep 17 00:00:00 2001
From: lordtet <lordtet@foxcarries.me>
Date: Fri, 4 Jul 2025 01:47:44 -0400
Subject: [PATCH] Serial output works!

---
 include/serial.h | 12 ++++++------
 src/main.c       | 10 +++++++++-
 src/serial.c     | 36 ++++++++++++++++++++++--------------
 3 files changed, 37 insertions(+), 21 deletions(-)

diff --git a/include/serial.h b/include/serial.h
index 6b044ad..f85526e 100644
--- a/include/serial.h
+++ b/include/serial.h
@@ -9,9 +9,9 @@
 #include "io.h"
 #include <stdint.h>
 
-typedef struct SerialState_s {
+typedef struct serial_ctx_s {
     uint16_t port;
-} SerialState_t;
+} serial_ctx_t;
 
 extern char_writer_t* default_COM;
 
@@ -20,7 +20,7 @@ extern char_writer_t* default_COM;
  * @param port The serial port number to initialize
  * @return Status code indicating success or failure
  */
-int serial_init(uint16_t port);
+int serial_init(serial_ctx_t* ctx);
 
 /**
  * @brief Check if there is pending data to receive on the serial port
@@ -32,19 +32,19 @@ int serial_recv_pending();
  * @brief Receive a single byte from the serial port
  * @return The received byte as an 8-bit unsigned integer
  */
-uint8_t serial_recv8(uint16_t port);
+uint8_t serial_recv8(serial_ctx_t* ctx);
 
 /**
  * @brief Check if the serial port is ready to send data
  * @return Non-zero if ready to send, 0 otherwise
  */
-int serial_send_pending(uint16_t port);
+int serial_send_pending(serial_ctx_t* ctx);
 
 /**
  * @brief Send a single byte through the serial port
  * @param data The 8-bit data byte to send
  */
-int serial_send8(uint16_t port, char data);
+int serial_send8(void* ctx, char data);
 
 
 #endif
diff --git a/src/main.c b/src/main.c
index 7ca8b88..3cbfbf2 100644
--- a/src/main.c
+++ b/src/main.c
@@ -25,7 +25,16 @@ void kern_main(uint32_t multiboot_magic, mb_info_t* multiboot_info)
     default_vga = &vga_writer;
     vga_clear_ctx(&vga_ctx);
 
+    //Serial prep
+    serial_ctx_t serial_ctx;
+    serial_ctx.port = COM1;
+    char_writer_t serial_writer;
+    serial_writer.ctx = &serial_ctx;
+    serial_writer.putChar = serial_send8;
+    default_COM = &serial_writer;
+    serial_init(&serial_ctx); 
 
+    
     printf(&vga_writer, "Entry eax:%X\n", multiboot_magic);
 
     if(multiboot_magic != 0x2BADB002) {
@@ -34,7 +43,6 @@ void kern_main(uint32_t multiboot_magic, mb_info_t* multiboot_info)
     } else {
         println(&vga_writer, "Multiboot detected! Continuing...");
     }
-
     printf(&vga_writer, "MEM_LOWER:%X\n", multiboot_info->mem_lower);
     printf(&vga_writer, "MEM_UPPER:%X\n", multiboot_info->mem_upper);
 }
diff --git a/src/serial.c b/src/serial.c
index 3d21ee1..37ac718 100644
--- a/src/serial.c
+++ b/src/serial.c
@@ -3,11 +3,12 @@
 
 char_writer_t* default_COM = 0;
 
-int serial_init(uint16_t port) {
+int serial_init(serial_ctx_t* ctx) {
+
     //disable interrupts when messing with it
-    outb(port + 1, 0x00);
+    outb(ctx->port + 1, 0x00);
     //set the dlab latch in order to make the baud rate accessible. In binary for clarity.
-    outb(port + 3, 0b10000000);
+    outb(ctx->port + 3, 0b10000000);
     
     //Sets the baud rate. Quick except on baud rate:
     //internal clock for the serial controller is 115200 ticks/sec. Or 115200hz. 
@@ -18,44 +19,51 @@ int serial_init(uint16_t port) {
     //(Source:https://wiki.osdev.org/Serial_Ports#Baud_Rate)
 
     //Baud lo byte
-    outb(port, 0x03);
+    outb(ctx->port, 0x03);
     //Baud hi byte
-    outb(port+1, 0x00);
+    outb(ctx->port+1, 0x00);
 
     //Again from OSWiki we're going to use their defaults for now.
     //DLAB off
     //Parity=0(no Parity)
     //One stop bit (set to 0)
     //Transmit in units of 8 bits
-    outb(port+3, 0b00000011);
+    outb(ctx->port+3, 0b00000011);
 
     //FIFO Control register
     //14 bit threshold for interrupt trigger
     //flush and enable FIFOs.
-    outb(port+2, 0b11000111);
+    outb(ctx->port+2, 0b11000111);
 
     //Enable IRQs + DTR + RTS
     //Nicely explained here: https://stackoverflow.com/questions/957337/what-is-the-difference-between-dtr-dsr-and-rts-cts-flow-control
     //In the future, this will be referred to 0x0B.
-    outb(port+4, 0b00001011);
+    outb(ctx->port+4, 0b00001011);
 
     //done! Let's test our chip. put it in loopback mode.
-    outb(port+4, 0x1E);
+    outb(ctx->port+4, 0x1E);
     //Lets try sending C4 (boom!) to test it
-    outb(port, 0xC4);
+    outb(ctx->port, 0xC4);
     
-    if(inb(port) != 0xC4) {
+    if(inb(ctx->port) != 0xC4) {
         //Boo womp
         return 1;
     }
 
     //we're good! All set up. Lets put it back into normal operational mode and gtfo.
-    outb(port+4, 0x0B);
+    outb(ctx->port+4, 0x0B);
     return 0;
 
 }
 
-int serial_send_pending(uint16_t port) {
+int serial_send_pending(serial_ctx_t* ctx) {
     //Bit 5 of the line status register has our output queue, essentially
-    return !(inb(port + 5) & 0x20);
+    return !(inb(ctx->port + 5) & 0x20);
+}
+
+int serial_send8(void* ctx, char out) {
+    serial_ctx_t* serial_ctx = (serial_ctx_t*) ctx;
+    while(serial_send_pending(serial_ctx));
+    outb(serial_ctx->port, out);
+    return 0;
 }