From a7a959a677efe79259d0311809b8d1c6ce82aa94 Mon Sep 17 00:00:00 2001
From: Bertold Van den Bergh <vandenbergh@bertold.org>
Date: Thu, 26 Aug 2021 16:27:41 +0200
Subject: [PATCH] Access TVD regs from main loop to avoid concurrent access

---
 mshal/hal_patch_tvdsafe.go | 65 ++++++++++++++++++++++++++++++++++++++
 mshal/hal_region.go        |  8 +++++
 2 files changed, 73 insertions(+)
 create mode 100644 mshal/hal_patch_tvdsafe.go

diff --git a/mshal/hal_patch_tvdsafe.go b/mshal/hal_patch_tvdsafe.go
new file mode 100644
index 0000000..49e0ed8
--- /dev/null
+++ b/mshal/hal_patch_tvdsafe.go
@@ -0,0 +1,65 @@
+package mshal
+
+type halPatchTVDMemoryRegion struct {
+	hal *HAL
+}
+
+func (h halPatchTVDMemoryRegion) GetName() MemoryRegionNameType {
+	return MemoryRegionRegisters2106TVD
+}
+
+func (h halPatchTVDMemoryRegion) GetLength() int {
+	return 256
+}
+
+func (h halPatchTVDMemoryRegion) GetParent() (MemoryRegion, int) {
+	return nil, 0
+}
+
+func (h halPatchTVDMemoryRegion) read(addr int, buf []byte) (int, error) {
+	req := PatchExecFuncRequest{
+		R7_A: uint8(addr),
+	}
+
+	resp, err := h.hal.PatchExecFunc(false, 0x3a33, req)
+	if err != nil {
+		return 0, err
+	}
+
+	buf[0] = resp.R7
+	return 1, nil
+}
+
+func (h halPatchTVDMemoryRegion) write(addr int, buf []byte) (int, error) {
+	req := PatchExecFuncRequest{
+		R5:   uint8(buf[0]),
+		R7_A: uint8(addr),
+	}
+
+	_, err := h.hal.PatchExecFunc(false, 0x3a17, req)
+	if err != nil {
+		return 0, err
+	}
+
+	return 1, nil
+}
+
+func (h halPatchTVDMemoryRegion) Access(write bool, addr int, buf []byte) (int, error) {
+	if len(buf) == 0 {
+		return 0, nil
+	}
+
+	if write {
+		return h.write(addr, buf)
+	}
+
+	return h.read(addr, buf)
+}
+
+func (h *HAL) patchMakeTVDRegion() MemoryRegion {
+	if !h.patchInstalled {
+		return nil
+	}
+
+	return regionWrapCompleteIO(halPatchTVDMemoryRegion{hal: h})
+}
diff --git a/mshal/hal_region.go b/mshal/hal_region.go
index fb76860..df455b8 100644
--- a/mshal/hal_region.go
+++ b/mshal/hal_region.go
@@ -80,6 +80,14 @@ func (h *HAL) MemoryRegionGet(name MemoryRegionNameType) MemoryRegion {
 			return regionWrapPartial(MemoryRegionUserConfig, h.MemoryRegionGet(MemoryRegionUserRAM), 0x3F0, 0x10)
 
 		case MemoryRegionRegisters2106TVD:
+			if h.patchInstalled {
+				if h.config.LogFunc != nil {
+					h.config.LogFunc(1, "Using patched TVD access")
+				}
+
+				return h.patchMakeTVDRegion()
+			}
+
 			return h.memoryRegionRegisters2106TVD()
 		}
 	}