From 9f69b122d0df699a454780e4464967d74f259564 Mon Sep 17 00:00:00 2001
From: Rekai Musuka <rekai@musuka.dev>
Date: Fri, 21 Oct 2022 05:12:46 -0300
Subject: [PATCH] chore: remove awful ptr casts in backup.zig and bios.zig

---
 src/Bus.zig         |  9 ++++++---
 src/bus/Bios.zig    |  5 ++---
 src/bus/GamePak.zig |  2 +-
 src/bus/backup.zig  | 16 ++--------------
 src/cpu.zig         |  4 ++--
 5 files changed, 13 insertions(+), 23 deletions(-)

diff --git a/src/Bus.zig b/src/Bus.zig
index f4eaa9a..aa456da 100644
--- a/src/Bus.zig
+++ b/src/Bus.zig
@@ -75,7 +75,10 @@ pub fn debugRead(self: *const Self, comptime T: type, address: u32) T {
     const cached = self.sched.tick;
     defer self.sched.tick = cached;
 
-    return self.read(T, address);
+    // FIXME: This is bad but it's a debug read so I don't care that much?
+    const this = @intToPtr(*Self, @ptrToInt(self));
+
+    return this.read(T, address);
 }
 
 fn readOpenBus(self: *const Self, comptime T: type, address: u32) T {
@@ -107,13 +110,13 @@ fn readOpenBus(self: *const Self, comptime T: type, address: u32) T {
     return @truncate(T, rotr(u32, word, 8 * (address & 3)));
 }
 
-fn readBios(self: *const Self, comptime T: type, address: u32) T {
+fn readBios(self: *Self, comptime T: type, address: u32) T {
     if (address < Bios.size) return self.bios.checkedRead(T, self.cpu.?.r[15], alignAddress(T, address));
 
     return self.readOpenBus(T, address);
 }
 
-pub fn read(self: *const Self, comptime T: type, address: u32) T {
+pub fn read(self: *Self, comptime T: type, address: u32) T {
     const page = @truncate(u8, address >> 24);
     const align_addr = alignAddress(T, address);
     self.sched.tick += 1;
diff --git a/src/bus/Bios.zig b/src/bus/Bios.zig
index bdf916e..8e2ec01 100644
--- a/src/bus/Bios.zig
+++ b/src/bus/Bios.zig
@@ -31,11 +31,10 @@ pub fn deinit(self: Self) void {
     if (self.buf) |buf| self.alloc.free(buf);
 }
 
-pub fn checkedRead(self: *const Self, comptime T: type, r15: u32, addr: u32) T {
+pub fn checkedRead(self: *Self, comptime T: type, r15: u32, addr: u32) T {
     if (r15 < Self.size) {
         // FIXME: Just give up on *const Self on bus reads, Rekai
-        const this = @intToPtr(*Self, @ptrToInt(self));
-        this.addr_latch = addr;
+        self.addr_latch = addr;
 
         return self.read(T, addr);
     }
diff --git a/src/bus/GamePak.zig b/src/bus/GamePak.zig
index 4ae26fa..d5d31fb 100644
--- a/src/bus/GamePak.zig
+++ b/src/bus/GamePak.zig
@@ -65,7 +65,7 @@ pub fn deinit(self: Self) void {
     self.backup.deinit();
 }
 
-pub fn read(self: *const Self, comptime T: type, address: u32) T {
+pub fn read(self: *Self, comptime T: type, address: u32) T {
     const addr = address & 0x1FF_FFFF;
 
     if (self.backup.kind == .Eeprom) {
diff --git a/src/bus/backup.zig b/src/bus/backup.zig
index 1f856e6..efe8277 100644
--- a/src/bus/backup.zig
+++ b/src/bus/backup.zig
@@ -333,20 +333,8 @@ const Eeprom = struct {
         };
     }
 
-    pub fn read(self: *const Self) u1 {
-        // Here I throw away the const qualifier which is bad and dumb but here's why.
-        // This is one of the few (as of when I write this, **only**) places that mutate
-        // some value upon access. Before this I've been able to have all read-related functions
-        // present a *const Self parameter with no issues.
-        //
-        // I don't think it's worth throwing away all the good that *const Self brings across the entire
-        // memory bus because reading from the EEPROM increments an internal counter which isn't even
-        // visible to neither the cartridge nor any other component of the emulator.
-        //
-        // By throwing away const, we can increment self.read_proc.i which has a range of 0 -> 67. This is
-        // a small enough scope (and a well defined one at that) so that this transgression isn't the worst, I think.
-        const self_mut = @intToPtr(*Self, @ptrToInt(self));
-        return self_mut.reader.read();
+    pub fn read(self: *Self) u1 {
+        return self.reader.read();
     }
 
     pub fn write(self: *Self, word_count: u16, buf: *[]u8, bit: u1) void {
diff --git a/src/cpu.zig b/src/cpu.zig
index da70be4..d4d09a7 100644
--- a/src/cpu.zig
+++ b/src/cpu.zig
@@ -336,11 +336,11 @@ pub const Arm7tdmi = struct {
         prettyPrintPsr(&self.spsr);
 
         if (self.cpsr.t.read()) {
-            const opcode = self.bus.read(u16, self.r[15] - 4);
+            const opcode = self.bus.debugRead(u16, self.r[15] - 4);
             const id = thumbIdx(opcode);
             std.debug.print("opcode: ID: 0x{b:0>10} 0x{X:0>4}\n", .{ id, opcode });
         } else {
-            const opcode = self.bus.read(u32, self.r[15] - 4);
+            const opcode = self.bus.debugRead(u32, self.r[15] - 4);
             const id = armIdx(opcode);
             std.debug.print("opcode: ID: 0x{X:0>3} 0x{X:0>8}\n", .{ id, opcode });
         }