Get rid of STRICTVIP and drawQuirk

Author: Timendus

docs/index.html

@@ -53,18 +53,14 @@ <h3>Interpreter type</h3>
 				</label>
 				<label>
 					<input type="radio" class="nes-radio is-dark" name="interpreter" value="1">
-					<span>Strict VIP</span>
-				</label>
-				<label>
-					<input type="radio" class="nes-radio is-dark" name="interpreter" value="2">
 					<span>VIP</span>
 				</label>
 				<label>
-					<input type="radio" class="nes-radio is-dark" name="interpreter" value="4">
+					<input type="radio" class="nes-radio is-dark" name="interpreter" value="3">
 					<span>SCHIP</span>
 				</label>
 				<label>
-					<input type="radio" class="nes-radio is-dark" name="interpreter" value="5">
+					<input type="radio" class="nes-radio is-dark" name="interpreter" value="4">
 					<span>XO-CHIP</span>
 				</label>
 			</div>

shared/types.js

@@ -1,8 +1,7 @@
 module.exports = {
-  AUTO:      0,
-  STRICTVIP: 1,  // Note that these two halt for display refresh, use BLINDVIP
-  VIP:       2,  // instead for headless testing
-  BLINDVIP:  3,
-  SCHIP:     4,
-  XOCHIP:    5
+  AUTO:      0, // Note that this one halts for display refresh, use BLINDVIP
+  VIP:       1, // instead for headless testing
+  BLINDVIP:  2,
+  SCHIP:     3,
+  XOCHIP:    4
 };

src/silicon8/cpu.go

@@ -71,9 +71,6 @@ func (cpu *CPU) Reset(interpreter int) {
 	}
 
 	switch interpreter {
-	case STRICTVIP:
-		cpu.RAMSize = STRICTVIP_RAM_SIZE
-		cpu.stackSize = DEFAULT_STACK_SIZE
 	case VIP, BLINDVIP:
 		cpu.RAMSize = VIP_SCHIP_RAM_SIZE
 		cpu.stackSize = DEFAULT_STACK_SIZE
@@ -134,10 +131,9 @@ func (cpu *CPU) setQuirks() {
 	cpu.shiftQuirk = cpu.specType == SCHIP
 	cpu.jumpQuirk = cpu.specType == SCHIP
 	cpu.memQuirk = cpu.specType != SCHIP
-	cpu.vfQuirk = cpu.specType == VIP || cpu.specType == STRICTVIP || cpu.specType == BLINDVIP
+	cpu.vfQuirk = cpu.specType == VIP || cpu.specType == BLINDVIP
 	cpu.clipQuirk = cpu.specType != XOCHIP
-	cpu.dispQuirk = cpu.specType == VIP || cpu.specType == STRICTVIP
-	cpu.drawQuirk = cpu.specType == STRICTVIP
+	cpu.dispQuirk = cpu.specType == VIP
 }
 
 func (cpu *CPU) DumpStatus() {
@@ -157,7 +153,6 @@ func (cpu *CPU) DumpStatus() {
 	println("   vfQuirk:   ", cpu.vfQuirk)
 	println("   clipQuirk: ", cpu.clipQuirk)
 	println("   dispQuirk: ", cpu.dispQuirk)
-	println("   drawQuirk: ", cpu.drawQuirk)
 }
 
 func (cpu *CPU) bumpSpecType(newType int) {

src/silicon8/display.go

@@ -120,7 +120,6 @@ func (cpu *CPU) draw(x, y, n uint8 ) {
 
   cpu.SD = true
   cpu.setFlag(erases)
-	cpu.messUpRegisters(x, y)
 	if n == 0 {
 		cpu.bumpSpecType(SCHIP)
 	}
@@ -169,22 +168,6 @@ func (cpu *CPU) drawLine(ramPointer uint16, planeBufPointer uint16, plane uint8)
   return erases
 }
 
-func (cpu *CPU) messUpRegisters(x, y uint8) {
-	if !cpu.drawQuirk {
-		return
-	}
-
-	/**
-	 * "First is that I, VX and VY are all altered by this routine, so the
-	 * Chip-8 programmer should not expect them to be available for reuse with
-	 * their original values. These would have to be explicitly set again."
-	 * -- https://laurencescotford.com/chip-8-on-the-cosmac-vip-drawing-sprites/
-	 **/
-	cpu.i = 0
-	cpu.v[x] = 0
-	cpu.v[y] = 0
-}
-
 func (cpu *CPU) initDisplay(width uint16, height uint16, planes uint8) {
 	cpu.DispWidth = width
 	cpu.DispHeight = height

src/silicon8/types.go

@@ -1,13 +1,11 @@
 package silicon8
 
 const AUTO      int = 0
-const STRICTVIP int = 1
-const VIP       int = 2
-const BLINDVIP  int = 3  // To run the emulator in headless VIP mode, which doesn't wait for display refresh
-const SCHIP     int = 4
-const XOCHIP    int = 5
+const VIP       int = 1
+const BLINDVIP  int = 2  // To run the emulator in headless VIP mode, which doesn't wait for display refresh
+const SCHIP     int = 3
+const XOCHIP    int = 4
 
-const STRICTVIP_RAM_SIZE uint16 = 3216 + 512
 const VIP_SCHIP_RAM_SIZE uint16 = 3583 + 512
 const XOCHIP_RAM_SIZE    uint16 = 65023 + 512
 const DEFAULT_STACK_SIZE uint8  = 12
@@ -62,7 +60,6 @@ type CPU struct {
 	vfQuirk        bool // vF is cleared after OR, AND and XOR opcodes
 	clipQuirk      bool // Sprites are clipped instead of wrapped at edges of display
 	dispQuirk      bool // Halt for display refresh before drawing sprite
-	drawQuirk      bool // Draw instruction messes up i, v[x] and v[y]
 
 	// External event handlers
 	playSound      playSoundEvent