snes: hirom: add missing LowRAM WRAM mappings

alttpo · Jun 20, 2021 · ecca4c1 · ecca4c1
1 parent 1513ec2
commit ecca4c1
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Showing 2 changed files with 79 additions and 14 deletions.
diff --git a/snes/mapping/hirom/mapping.go b/snes/mapping/hirom/mapping.go
@@ -19,10 +19,15 @@ func BusAddressToPak(busAddr uint32) uint32 {
 			rom := util.BankToLinear(busAddr&0x3F7FFF) + 0x000000
 			return rom
 		} else if busAddr&0x7FFF >= 0x6000 {
+			// TODO: A0-AF, B0-BF mirroring?
 			// SRAM access:        $A0:6000-$BF:7FFF
 			bank := (busAddr >> 16) - 0xA0
 			sram := ((bank << 13) + (busAddr & 0x1FFF)) + 0xE00000
 			return sram
+		} else if busAddr&0xFFFF < 0x2000 {
+			// Lower 8KiB of WRAM: $A0:0000-$BF:1FFF
+			wram := (busAddr & 0x1FFF) + 0xF50000
+			return wram
 		}
 	} else if busAddr >= 0x800000 && busAddr < 0xA00000 {
 		if busAddr&0x8000 != 0 {
@@ -48,10 +53,15 @@ func BusAddressToPak(busAddr uint32) uint32 {
 			rom := util.BankToLinear(busAddr&0x3F7FFF) + 0x000000
 			return rom
 		} else if busAddr&0x7FFF >= 0x6000 {
+			// TODO: 20-2F, 30-3F mirroring?
 			// SRAM access:        $20:6000-$3F:7FFF
 			bank := (busAddr >> 16) - 0x20
 			sram := ((bank << 13) + (busAddr & 0x1FFF)) + 0xE00000
 			return sram
+		} else if busAddr&0xFFFF < 0x2000 {
+			// Lower 8KiB of WRAM: $00:0000-$1F:1FFF
+			wram := (busAddr & 0x1FFF) + 0xF50000
+			return wram
 		}
 	} else if busAddr >= 0x000000 && busAddr < 0x200000 {
 		if busAddr&0x8000 != 0 {
@@ -74,33 +84,31 @@ func PakAddressToBus(pakAddr uint32) uint32 {
 		// are not available on the SNES bus; they are copies of otherwise inaccessible memory
 		// like VRAM, CGRAM, OAM, etc.:
 		return ((pakAddr - 0xF50000) & 0x01FFFF) + 0x7E0000
-	}
-	// SRAM is a little more complex, but not much:
-	if pakAddr >= 0xE00000 && pakAddr < 0xF00000 {
+	} else if pakAddr >= 0xE00000 && pakAddr < 0xF00000 {
+		// SRAM is a little more complex, but not much:
 		// bank $A0-$BF
 		busAddr := pakAddr - 0xE00000
 		offs := busAddr & 0x1FFF
 		bank := (busAddr >> 13) & 0x1F
 		busAddr = ((0xA0 + bank) << 16) + (offs + 0x6000)
 		return busAddr
-	}
-	// ROM access:
-	// HiROM is limited to $40 full banks
-	if pakAddr < 0x200000 {
+	} else if pakAddr >= 0x200000 && pakAddr < 0xE00000 {
+		busAddr := pakAddr & 0x3FFFFF
+		// Accessing memory in banks $80-$FF is done at 3.58 MHz (120 ns) if the value at address $420D (hardware register) is set to 1.
+		// Starting at $C0 gets us the full linear mapping of ROM without having to cut up in $8000 sized chunks:
+		busAddr = 0xC00000 + busAddr
+		return busAddr
+	} else if pakAddr < 0x200000 {
+		// ROM access:
+		// HiROM is limited to $40 full banks
+
 		// use SlowROM banks $00-$3F:
 		busAddr := pakAddr & 0x3FFFFF
 		offs := busAddr & 0x7FFF
 		bank := busAddr >> 15
 		busAddr = ((0x00 + bank) << 16) + (offs | 0x8000)
 		return busAddr
 	}
-	if pakAddr < 0xE00000 {
-		busAddr := pakAddr & 0x3FFFFF
-		// Accessing memory in banks $80-$FF is done at 3.58 MHz (120 ns) if the value at address $420D (hardware register) is set to 1.
-		// Starting at $C0 gets us the full linear mapping of ROM without having to cut up in $8000 sized chunks:
-		busAddr = 0xC00000 + busAddr
-		return busAddr
-	}
 	// /shrug
 	return pakAddr
 }
diff --git a/snes/mapping/hirom/mapping_test.go b/snes/mapping/hirom/mapping_test.go
@@ -475,6 +475,34 @@ func TestBusAddressToPak(t *testing.T) {
 			},
 			want: 0xF51FFF,
 		},
+		{
+			name: "WRAM bank $A0:0000",
+			args: args{
+				busAddr: 0xA00000,
+			},
+			want: 0xF50000,
+		},
+		{
+			name: "WRAM bank $A0:1FFF",
+			args: args{
+				busAddr: 0xA01FFF,
+			},
+			want: 0xF51FFF,
+		},
+		{
+			name: "WRAM bank $BF:0000",
+			args: args{
+				busAddr: 0xBF0000,
+			},
+			want: 0xF50000,
+		},
+		{
+			name: "WRAM bank $BF:1FFF",
+			args: args{
+				busAddr: 0xBF1FFF,
+			},
+			want: 0xF51FFF,
+		},
 		// WRAM banks 7E-7F:
 		{
 			name: "WRAM bank $7E:0000",
@@ -596,6 +624,7 @@ func TestBusAddressToPak(t *testing.T) {
 			},
 			want: 0xE3FFFF,
 		},
+		// WRAM:
 		{
 			name: "WRAM bank $00:0000",
 			args: args{
@@ -624,6 +653,34 @@ func TestBusAddressToPak(t *testing.T) {
 			},
 			want: 0xF51FFF,
 		},
+		{
+			name: "WRAM bank $20:0000",
+			args: args{
+				busAddr: 0x200000,
+			},
+			want: 0xF50000,
+		},
+		{
+			name: "WRAM bank $20:1FFF",
+			args: args{
+				busAddr: 0x201FFF,
+			},
+			want: 0xF51FFF,
+		},
+		{
+			name: "WRAM bank $3F:0000",
+			args: args{
+				busAddr: 0x3F0000,
+			},
+			want: 0xF50000,
+		},
+		{
+			name: "WRAM bank $3F:1FFF",
+			args: args{
+				busAddr: 0x3F1FFF,
+			},
+			want: 0xF51FFF,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {