From 748471a5310f2413afc26c00b282ade64e718a3e Mon Sep 17 00:00:00 2001
From: James Barnett <noreply@jamesbarnett.xyz>
Date: Sun, 8 Jul 2018 17:47:02 +0100
Subject: Implement 16-Bit arithmetic ops

---
 src/main/kotlin/cpu/opcodes/Arithmetic16Bit.kt | 60 ++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)
 create mode 100644 src/main/kotlin/cpu/opcodes/Arithmetic16Bit.kt

(limited to 'src/main/kotlin/cpu/opcodes/Arithmetic16Bit.kt')

diff --git a/src/main/kotlin/cpu/opcodes/Arithmetic16Bit.kt b/src/main/kotlin/cpu/opcodes/Arithmetic16Bit.kt
new file mode 100644
index 0000000..0c2c9cb
--- /dev/null
+++ b/src/main/kotlin/cpu/opcodes/Arithmetic16Bit.kt
@@ -0,0 +1,60 @@
+package cpu.opcodes
+
+import cpu.Operation
+import cpu.Registers
+import cpu.Registers.Flag
+import BitManipulation as bm
+
+var arithmetic16Bit = mapOf(
+
+  0x09 to Operation("ADD HL,BC", 0, 8, {r, _, _ -> r.HL = add(r.HL, r.BC, r)}),
+  0x19 to Operation("ADD HL,DE", 0, 8, {r, _, _ -> r.HL = add(r.HL, r.DE, r)}),
+  0x29 to Operation("ADD HL,HL", 0, 8, {r, _, _ -> r.HL = add(r.HL, r.HL, r)}),
+  0x39 to Operation("ADD HL,SP", 0, 8, {r, _, _ -> r.HL = add(r.HL, r.SP, r)}),
+
+  0xE8 to Operation("ADD SP,n", 1, 16, {r, _, a ->
+    r.clearFlags()
+
+    val absoluteValue = bm.getAbsoluteValue(a[0])
+
+    if (bm.isSignedBitNegative(a[0])) {
+      r.setFlagFromBool(Flag.HALF_CARRY, r.SP and 0x0F < absoluteValue and 0x0F)
+      r.setFlagFromBool(Flag.CARRY,r.SP and 0xFF < absoluteValue)
+      r.SP = r.SP - absoluteValue
+
+    } else {
+      r.setFlagFromBool(Flag.HALF_CARRY,(r.SP and 0x0F) + (absoluteValue and 0x0F) > 0x0F)
+      r.setFlagFromBool(Flag.CARRY,(r.SP and 0xFF) + absoluteValue > 0xFF)
+      r.SP = r.SP + absoluteValue
+    }
+  }),
+
+  0x03 to Operation("INC BC", 0, 8, {r, _, _ -> r.BC = inc(r.BC)}),
+  0x13 to Operation("INC DE", 0, 8, {r, _, _ -> r.DE = inc(r.DE)}),
+  0x23 to Operation("INC HL", 0, 8, {r, _, _ -> r.HL = inc(r.HL)}),
+  0x33 to Operation("INC SP", 0, 8, {r, _, _ -> r.SP = inc(r.SP)}),
+
+  0x0B to Operation("DEC BC", 0, 8, {r, _, _ -> r.BC = dec(r.BC)}),
+  0x1B to Operation("DEC DE", 0, 8, {r, _, _ -> r.DE = dec(r.DE)}),
+  0x2B to Operation("DEC HL", 0, 8, {r, _, _ -> r.HL = dec(r.HL)}),
+  0x3B to Operation("DEC SP", 0, 8, {r, _, _ -> r.SP = dec(r.SP)})
+
+)
+
+private fun add(n1: Int, n2: Int, r: Registers): Int {
+
+  r.clearFlag(Flag.SUBTRACT)
+  r.setFlagFromBool(Flag.HALF_CARRY, ((n1 and 0x0FFF) + (n2 and 0x0FFF)) > 0x0FFF)
+  r.setFlagFromBool(Flag.CARRY, (n1 + n2) > 0xFFFF)
+
+  return (n1 + n2) and 0xFFFF
+}
+
+
+private fun inc(n: Int): Int {
+  return (n + 1) and 0xFFFF
+}
+
+private fun dec(n: Int): Int {
+  return (n - 1) and 0xFFFF
+}
\ No newline at end of file
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