snes: exhirom: complete BusAddressToPak mapping

alttpo · Jun 20, 2021 · 379a9b8 · 379a9b8
1 parent ecca4c1
commit 379a9b8
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Showing 2 changed files with 417 additions and 8 deletions.
diff --git a/snes/mapping/exhirom/mapping.go b/snes/mapping/exhirom/mapping.go
@@ -1,18 +1,83 @@
 package exhirom
 
-import (
-	"sni/snes/mapping/util"
-)
+import "sni/snes/mapping/util"
 
 // https://thepoorstudenthobbyist.com/2019/05/18/custom-pcb-explanation/#exhirom
 
 func BusAddressToPak(busAddr uint32) uint32 {
-	if busAddr&0x8000 == 0 {
-		if busAddr >= 0x700000 && busAddr < 0x7E0000 {
-			sram := util.BankToLinear(busAddr-0x700000) + 0xE00000
+	if busAddr >= 0xC00000 && busAddr < 0x1_000000 {
+		// program area 1
+		// ROM access:             $C0:0000-$FF:FFFF
+		rom := (busAddr & 0x3FFFFF) + 0x000000
+		return rom
+	} else if busAddr >= 0xA00000 && busAddr < 0xC00000 {
+		if busAddr&0x8000 != 0 {
+			// program area 1
+			// ROM access:         $A0:8000-$BF:FFFF
+			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 >= 0x7E0000 && busAddr < 0x800000 {
-			wram := (busAddr - 0x7E0000) + 0xF50000
+		} 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 {
+			// program area 1
+			// ROM access:         $80:8000-$9F:FFFF
+			rom := util.BankToLinear(busAddr&0x3F7FFF) + 0x000000
+			return rom
+		} else if busAddr&0xFFFF < 0x2000 {
+			// Lower 8KiB of WRAM: $80:0000-$9F:1FFF
+			wram := (busAddr & 0x1FFF) + 0xF50000
+			return wram
+		}
+	} else if busAddr >= 0x7E0000 && busAddr < 0x800000 {
+		// WRAM access:
+		wram := (busAddr - 0x7E0000) + 0xF50000
+		return wram
+	} else if busAddr >= 0x400000 && busAddr < 0x7E0000 {
+		// program area 2
+		// ROM access:             $40:0000-$7D:FFFF
+		rom := (busAddr & 0x3FFFFF) + 0x400000
+		return rom
+	} else if busAddr >= 0x3E0000 && busAddr < 0x400000 {
+		if busAddr&0x8000 != 0 {
+			// program area 3 $3E-3F
+			// ROM access:             $3E:8000-$3F:FFFF
+			rom := util.BankToLinear(busAddr&0x3F7FFF) + 0x400000
+			return rom
+		} else if busAddr&0xFFFF < 0x2000 {
+			// Lower 8KiB of WRAM: $00:0000-$1F:1FFF
+			wram := (busAddr & 0x1FFF) + 0xF50000
+			return wram
+		}
+	} else if busAddr >= 0x200000 && busAddr < 0x3E0000 {
+		if busAddr&0x8000 != 0 {
+			// program area 2
+			// ROM access:         $20:8000-$3D:FFFF
+			rom := util.BankToLinear(busAddr&0x3F7FFF) + 0x400000
+			return rom
+		} 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 {
+			// program area 2
+			// ROM access:         $00:8000-$1F:FFFF
+			rom := util.BankToLinear(busAddr&0x3F7FFF) + 0x400000
+			return rom
+		} else if busAddr&0xFFFF < 0x2000 {
+			// Lower 8KiB of WRAM: $00:0000-$1F:1FFF
+			wram := (busAddr & 0x1FFF) + 0xF50000
 			return wram
 		}
 	}
@@ -29,6 +94,7 @@ func PakAddressToBus(pakAddr uint32) uint32 {
 	}
 	// SRAM is a little more complex, but not much:
 	if pakAddr >= 0xE00000 && pakAddr < 0xF00000 {
+		// A0:6000-7FFF to BF:6000-7FFF
 		busAddr := pakAddr - 0xE00000
 		offs := busAddr & 0x1FFF
 		bank := (busAddr >> 13) & 0x1F
@@ -47,18 +113,23 @@ func PakAddressToBus(pakAddr uint32) uint32 {
 			if bank >= 0x7E {
 				bank += 0x80
 			}
+			// $00:8000-FFFF to $7D:8000-FFFF
+			// $FE:8000-FFFF to $FF:8000-FFFF
 			busAddr = (bank << 16) + (offs | 0x8000)
 		} else if pakAddr >= 0x7E0000 && pakAddr < 0x800000 {
 			// program ROM area 3 is top half of banks $3E and $3F
 			busAddr = pakAddr - 0x7E0000
 			offs := busAddr & 0x7FFF
 			bank := 0x3E + (busAddr >> 15)
+			// $3E:8000-FFFF to $3F:8000-FFFF
 			busAddr = (bank << 16) + (offs | 0x8000)
 		} else if pakAddr >= 0x400000 && pakAddr < 0x7E0000 {
 			// program ROM area 2 is full banks $40-$7D
+			// $40:0000-FFFF to $7D:0000-FFFF
 			busAddr = 0x400000 + (pakAddr & 0x3FFFFF)
 		} else {
 			// program ROM area 1 is full banks $C0-$FF
+			// $C0:0000-FFFF to $FF:0000-FFFF
 			busAddr = 0xC00000 + (pakAddr & 0x3FFFFF)
 		}
 		return busAddr