From 4f85bd4b1bdfbfcdae1563add081b3bc04682165 Mon Sep 17 00:00:00 2001
From: John Bintz <hello@theindustriousrabbit.com>
Date: Wed, 20 Mar 2024 09:02:47 -0400
Subject: [PATCH] more latch copy fun, write asm kb interrupt handler bc why
 not

---
 main.c  | 43 +++++++++++++++++++++++++++----
 vga.asm | 79 ++++++++++++++++++++++++++++++++++++++++++++++++++++-----
 2 files changed, 111 insertions(+), 11 deletions(-)

diff --git a/main.c b/main.c
index 58702b4..c2fee20 100644
--- a/main.c
+++ b/main.c
@@ -1,22 +1,29 @@
+#include <stdio.h>
 #include <i86.h>
 #include <conio.h>
 
 extern void __cdecl enableUnchainedVGAMode();
 extern void __cdecl enableTextMode();
 extern void __cdecl fillScreen(int);
-extern void __cdecl latchCopyCube();
+extern void __cdecl latchCopyCube(char offset, int writtenValue, int writeMode);
+extern int __cdecl paramTest(int wow);
+
+extern void __cdecl far interrupt keyboardHandler();
+extern char keyboardPressed;
 
 char far *VGA = (char*)0xA0000;
 
 #define PLANE_WIDTH (320 / 4)
 
+void far (interrupt *int9Save)();
+
 void populateExampleCube(void) {
   int y, x;
 
   outp(0x3c4, 0x02);
 
-  for (y = 0; y < 15; ++y) {
-    for (x = 0; x < 15; ++x) {
+  for (y = 0; y < 16; ++y) {
+    for (x = 0; x < 16; ++x) {
       outp(0x3c5, 1 << (x % 4));
       VGA[y * PLANE_WIDTH + x / 4] = y * 16 + x;
     }
@@ -34,14 +41,40 @@ int main(void) {
 
   int i,j;
 
+  int9Save = _dos_getvect(9);
+  _dos_setvect(9, keyboardHandler);
+
+  printf("%p\n", keyboardHandler);
+
+  while (keyboardPressed == 0) {
+    printf("%d\n", keyboardPressed);
+  }
+
+  printf("wow\n");
+  delay(200);
+
+  _dos_setvect(9, int9Save);
+
+  return 0;
+
   enableUnchainedVGAMode();
 
   fillScreen(0);
 
   populateExampleCube();
-  latchCopyCube();
+  latchCopyCube(8, 0, 0x00);
+  latchCopyCube(12, 127, 0x00);
+  latchCopyCube(16, 0, 0x08);
+  latchCopyCube(20, 127, 0x08);
+  latchCopyCube(24, 0, 0x10);
+  latchCopyCube(28, 127, 0x10);
+  latchCopyCube(32, 0, 0x18);
+  latchCopyCube(36, 127, 0x18);
+
+  while (keyboardPressed == 0) {
+    delay(1);
+  }
 
-  delay(2000);
 
   /*
 
diff --git a/vga.asm b/vga.asm
index 55c7995..9813a92 100644
--- a/vga.asm
+++ b/vga.asm
@@ -2,6 +2,9 @@ PUBLIC _enableUnchainedVGAMode
 PUBLIC _enableTextMode
 PUBLIC _fillScreen
 PUBLIC _latchCopyCube
+PUBLIC _paramTest
+PUBLIC _keyboardPressed
+PUBLIC _keyboardHandler
 
 DISPLAY_MODE_VGA equ 13h
 DISPLAY_MODE_TEXT equ 03h
@@ -23,8 +26,42 @@ VGA_CRT_CONTROLLER_MODE_CONTROL equ 0x17
 .386
 .model flat,c
 
+.DATA
+
+_keyboardPressed dd 0
+
 .CODE
 
+_keyboardHandler:
+  cli
+  push eax
+  push ebx
+
+  in al, 0x60
+  mov bl, al
+
+  ; acknowledge keyboard
+  in al, 0x61
+  mov ah, al
+  or al, 0x80
+  out 0x61, al
+  xchg ah, al
+  out 0x61, al
+
+  and bl,0x80
+  jne _keyboardHandler_notKeydown
+
+  mov [_keyboardPressed], 1
+_keyboardHandler_notKeydown:
+  ; acknowledge interrupt
+  mov al, 0x20
+  out 0x20, al
+
+  pop ebx
+  pop eax
+  sti
+  iretd
+
 _enableUnchainedVGAMode:
   mov ax,0x0013;
   int 0x10
@@ -76,24 +113,49 @@ _fillScreen_loop:
 
   ret
 
+_paramTest:
+  push ebp
+  mov ebp,esp
+
+  mov eax,0
+  mov al, BYTE PTR [ebp+8]
+
+  mov esp,ebp
+  pop ebp
+  ret
+
 _latchCopyCube:
   push ebp
   mov ebp,esp
   ; we need a y variable
   sub esp,4 ; y
 
-  ; enable latch reads
+  push edx
+  push ebx
+
+  ; accept a mode
+  ; accept a mix value
+  ; accept an x offset
+
+  ; [ebp+8] is x offset
+  ; [ebp+12] is written value
+  ; [ebp+16] is data rotate register
+
+  ; enable latch reads on all planes
   mov dx, VGA_SEQUENCE_CONTROLLER_INDEX
   mov al, VGA_SEQUENCE_CONTROLLER_MAP_MASK_MODE
   mov ah, 0xf
   out dx, ax
 
+  ; enable OR writes
   mov dx, VGA_GRAPHICS_MODE_INDEX
-  mov al, 0x08
-  mov ah, 0x00
+  mov al, 0x03
+  mov ah, [ebp+16]
   out dx, ax
 
-  mov DWORD PTR [ebp-4],16
+  mov dh, [ebp+12]
+
+  mov DWORD PTR [ebp-4],16 ; y
   ; read across the cube, should take 4 * 16 reads
   mov cx,[ebp-4]
 _latchCopyCube_yLoop:
@@ -106,14 +168,17 @@ _latchCopyCube_yLoop:
   mul bl ; number of lines
   add eax,0xa0000 ; vga base address
 
+  ; keep our index handy
+  mov ebx, [ebp+8]
+
   ; start x loop
   mov cx,4
 _latchCopyCube_xLoop:
   ; fill latches via memory read
-  mov bl, BYTE PTR [eax]
+  mov dl, BYTE PTR [eax]
 
   ; write blank
-  mov [eax+12],0
+  mov BYTE PTR [eax+ebx], dh
 
   ; increment vga pointer
   inc eax
@@ -128,6 +193,8 @@ _latchCopyCube_xLoop:
   loop _latchCopyCube_yLoop
 
   ; put things back
+  pop ebx
+  pop edx
   mov esp,ebp
   pop ebp
   ret