checkpoint

1 files changed, 66 insertions, 0 deletions

diff --git a/src/sim86/libs/reference_decoder/sim86_memory.cpp b/src/sim86/libs/reference_decoder/sim86_memory.cpp
new file mode 100644
index 0000000..1d58ede
--- /dev/null
+++ b/src/sim86/libs/reference_decoder/sim86_memory.cpp
@@ -0,0 +1,66 @@
+/* ========================================================================
+
+   (C) Copyright 2023 by Molly Rocket, Inc., All Rights Reserved.
+   
+   This software is provided 'as-is', without any express or implied
+   warranty. In no event will the authors be held liable for any damages
+   arising from the use of this software.
+   
+   Please see https://computerenhance.com for more information
+   
+   ======================================================================== */
+
+static u32 GetHighestAddress(segmented_access SegMem)
+{
+    u32 Result = SegMem.Mask;
+    return Result;
+}
+
+static u32 GetAbsoluteAddressOf(u32 Mask, u16 SegmentBase, u16 SegmentOffset, u16 AdditionalOffset)
+{
+    u32 Result = (((u32)SegmentBase << 4) + (u32)(SegmentOffset + AdditionalOffset)) & Mask;
+    return Result;
+}
+
+static u32 GetAbsoluteAddressOf(segmented_access SegMem, u16 Offset)
+{
+    u32 Result = GetAbsoluteAddressOf(SegMem.Mask, SegMem.SegmentBase, SegMem.SegmentOffset, Offset);
+    return Result;
+}
+
+static segmented_access MoveBaseBy(segmented_access Access, s32 Offset)
+{
+    Access.SegmentOffset += Offset;
+    
+    segmented_access Result = Access;
+    
+    Result.SegmentBase += (Result.SegmentOffset >> 4);
+    Result.SegmentOffset &= 0xf;
+
+    assert(GetAbsoluteAddressOf(Result, 0) == GetAbsoluteAddressOf(Access, 0));
+    
+    return Result;
+}
+
+static u8 *AccessMemory(segmented_access SegMem, u16 Offset)
+{
+    u32 AbsAddr = GetAbsoluteAddressOf(SegMem, Offset);
+    u8 *Result = SegMem.Memory + AbsAddr;
+    return Result;
+}
+
+static b32 IsValid(segmented_access SegMem)
+{
+    b32 Result = (SegMem.Mask != 0);
+    return Result;
+}
+
+static segmented_access FixedMemoryPow2(u32 SizePow2, u8 *Memory)
+{
+    segmented_access Result = {};
+    
+    Result.Memory = Memory;
+    Result.Mask = (1 << SizePow2) - 1;
+    
+    return Result;
+}