From 8b015d9168e3de1ef63982892401081103cfb7b7 Mon Sep 17 00:00:00 2001
From: James Barnett <noreply@jamesbarnett.xyz>
Date: Thu, 12 Jul 2018 21:48:35 +0100
Subject: Add shift ops

---
 src/main/kotlin/cpu/opcodes/Shifts.kt | 73 +++++++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)
 create mode 100644 src/main/kotlin/cpu/opcodes/Shifts.kt

(limited to 'src/main/kotlin/cpu/opcodes/Shifts.kt')

diff --git a/src/main/kotlin/cpu/opcodes/Shifts.kt b/src/main/kotlin/cpu/opcodes/Shifts.kt
new file mode 100644
index 0000000..04e68bc
--- /dev/null
+++ b/src/main/kotlin/cpu/opcodes/Shifts.kt
@@ -0,0 +1,73 @@
+package cpu.opcodes
+
+import cpu.Operation
+import cpu.Registers
+import cpu.Registers.Flag
+import BitManipulation as bm
+
+val shiftsExtended = mapOf(
+
+  0x27 to Operation("SLA A", 0, 8, {r, _, _ -> r.A = shiftLeft(r.A, r) }),
+  0x20 to Operation("SLA B", 0, 8, {r, _, _ -> r.A = shiftLeft(r.B, r) }),
+  0x21 to Operation("SLA C", 0, 8, {r, _, _ -> r.A = shiftLeft(r.C, r) }),
+  0x22 to Operation("SLA D", 0, 8, {r, _, _ -> r.A = shiftLeft(r.D, r) }),
+  0x23 to Operation("SLA E", 0, 8, {r, _, _ -> r.A = shiftLeft(r.E, r) }),
+  0x24 to Operation("SLA H", 0, 8, {r, _, _ -> r.A = shiftLeft(r.H, r) }),
+  0x25 to Operation("SLA L", 0, 8, {r, _, _ -> r.A = shiftLeft(r.L, r) }),
+  0x26 to Operation("SLA (HL)", 0, 16, {r, m, _ ->  m.writeByte(r.HL, shiftLeft(m.readByte(r.HL), r))}),
+
+  0x2F to Operation("SRA A", 0, 8, {r, _, _ -> r.A = shiftRight(r.A, r) }),
+  0x28 to Operation("SRA B", 0, 8, {r, _, _ -> r.A = shiftRight(r.B, r) }),
+  0x29 to Operation("SRA C", 0, 8, {r, _, _ -> r.A = shiftRight(r.C, r) }),
+  0x2A to Operation("SRA D", 0, 8, {r, _, _ -> r.A = shiftRight(r.D, r) }),
+  0x2B to Operation("SRA E", 0, 8, {r, _, _ -> r.A = shiftRight(r.E, r) }),
+  0x2C to Operation("SRA H", 0, 8, {r, _, _ -> r.A = shiftRight(r.H, r) }),
+  0x2D to Operation("SRA L", 0, 8, {r, _, _ -> r.A = shiftRight(r.L, r) }),
+  0x2E to Operation("SRA (HL)", 0, 16, {r, m, _ ->  m.writeByte(r.HL, shiftRight(m.readByte(r.HL), r))}),
+
+  0x3F to Operation("SRL A", 0, 8, {r, _, _ -> r.A = shiftRightMsb0(r.A, r) }),
+  0x38 to Operation("SRL B", 0, 8, {r, _, _ -> r.A = shiftRightMsb0(r.B, r) }),
+  0x39 to Operation("SRL C", 0, 8, {r, _, _ -> r.A = shiftRightMsb0(r.C, r) }),
+  0x3A to Operation("SRL D", 0, 8, {r, _, _ -> r.A = shiftRightMsb0(r.D, r) }),
+  0x3B to Operation("SRL E", 0, 8, {r, _, _ -> r.A = shiftRightMsb0(r.E, r) }),
+  0x3C to Operation("SRL H", 0, 8, {r, _, _ -> r.A = shiftRightMsb0(r.H, r) }),
+  0x3D to Operation("SRL L", 0, 8, {r, _, _ -> r.A = shiftRightMsb0(r.L, r) }),
+  0x3E to Operation("SRL (HL)", 0, 16, {r, m, _ ->  m.writeByte(r.HL, shiftRightMsb0(m.readByte(r.HL), r))})
+
+)
+
+private fun shiftLeft(n: Int, r: Registers): Int {
+
+  val result = (n shl 1) and 0xFF
+
+  r.setFlagFromBool(Flag.ZERO, result == 0)
+  r.clearFlag(Flag.SUBTRACT)
+  r.clearFlag(Flag.HALF_CARRY)
+  r.setFlagFromBool(Flag.CARRY, (n and (1 shl 7)) != 0)
+
+  return result
+}
+
+private fun shiftRight(n: Int, r: Registers): Int {
+
+  val result = (n shr 1) or (n and (1 shl 7))
+
+  r.setFlagFromBool(Flag.ZERO, result == 0)
+  r.clearFlag(Flag.SUBTRACT)
+  r.clearFlag(Flag.HALF_CARRY)
+  r.setFlagFromBool(Flag.CARRY, (n and 1) != 0)
+
+  return result
+}
+
+private fun shiftRightMsb0(n: Int, r: Registers): Int {
+
+  val result = (n shr 1)
+
+  r.setFlagFromBool(Flag.ZERO, result == 0)
+  r.clearFlag(Flag.SUBTRACT)
+  r.clearFlag(Flag.HALF_CARRY)
+  r.setFlagFromBool(Flag.CARRY, (n and 1) != 0)
+
+  return result
+}
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