Initial files. Implement basic registers.

2 files changed, 248 insertions, 0 deletions

diff --git a/src/main/kotlin/Registers.kt b/src/main/kotlin/Registers.kt
new file mode 100644
index 0000000..e65a372
--- /dev/null
+++ b/src/main/kotlin/Registers.kt
@@ -0,0 +1,122 @@
+class Registers {
+
+  // General purpose registers
+  var B: Int = 0
+    set(value) {
+      validateUnsigned8Bit(value)
+      field = value
+    }
+  var C: Int = 0
+    set(value) {
+      validateUnsigned8Bit(value)
+      field = value
+    }
+  var D: Int = 0
+    set(value) {
+      validateUnsigned8Bit(value)
+      field = value
+    }
+  var E: Int = 0
+    set(value) {
+      validateUnsigned8Bit(value)
+      field = value
+    }
+  var H: Int = 0
+    set(value) {
+      validateUnsigned8Bit(value)
+      field = value
+    }
+  var L: Int = 0
+    set(value) {
+      validateUnsigned8Bit(value)
+      field = value
+    }
+
+  // Special registers
+  var A: Int = 0
+    set(value) {
+      validateUnsigned8Bit(value)
+      field = value
+    }
+  var F: Int = 0
+    set(value) {
+      validateUnsigned8Bit(value)
+      field = value
+    }
+  var SP: Int = 0
+    set(value) {
+      validateUnsigned16Bit(value)
+      field = value
+    }
+  var PC: Int = 0
+    set(value) {
+      validateUnsigned16Bit(value)
+      field = value
+    }
+
+  // 16-Bit accessors
+  var AF: Int
+    get() {
+      return bytesToWord(A, F)
+    }
+    set(value) {
+      validateUnsigned16Bit(value)
+      A = getMsb(value)
+      F = getLsb(value)
+    }
+
+  var BC: Int
+    get() {
+      return bytesToWord(B, C)
+    }
+    set(value) {
+      validateUnsigned16Bit(value)
+      B = getMsb(value)
+      C = getLsb(value)
+    }
+
+  var DE: Int
+    get() {
+      return bytesToWord(D, E)
+    }
+    set(value) {
+      validateUnsigned16Bit(value)
+      D = getMsb(value)
+      E = getLsb(value)
+    }
+
+  var HL: Int
+    get() {
+      return bytesToWord(H, L)
+    }
+    set(value) {
+      validateUnsigned16Bit(value)
+      H = getMsb(value)
+      L = getLsb(value)
+    }
+
+  private fun bytesToWord(msb: Int, lsb: Int): Int {
+    return msb.shl(8) + lsb
+  }
+
+  private fun getMsb(value: Int): Int {
+    return value.shr(8)
+  }
+
+  private fun getLsb(value: Int): Int {
+    return value.and(0xFF)
+  }
+
+  private fun validateUnsigned8Bit(value: Int) {
+    if(value < 0 || value > 255) {
+      throw IllegalArgumentException("Value $value is not an unsigned 8-Bit value")
+    }
+  }
+
+  private fun validateUnsigned16Bit(value: Int) {
+    if(value < 0 || value > 65535) {
+      throw IllegalArgumentException("Value $value is not an unsigned 16-Bit value")
+    }
+  }
+
+}
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diff --git a/src/test/kotlin/RegisterTest.kt b/src/test/kotlin/RegisterTest.kt
new file mode 100644
index 0000000..53daa2a
--- /dev/null
+++ b/src/test/kotlin/RegisterTest.kt
@@ -0,0 +1,126 @@
+import io.kotlintest.shouldBe
+import io.kotlintest.shouldThrow
+import io.kotlintest.specs.StringSpec
+import java.lang.IllegalArgumentException
+
+class RegisterTest : StringSpec({
+
+  "Test 16-Bit accessors" {
+    val reg = Registers()
+
+    reg.AF = 0xF83C
+    reg.AF shouldBe 0xF83C
+    reg.A shouldBe 0xF8
+    reg.F shouldBe 0x3C
+
+    reg.BC = 0xF83C
+    reg.BC shouldBe 0xF83C
+    reg.B shouldBe 0xF8
+    reg.C shouldBe 0x3C
+
+    reg.DE = 0xF83C
+    reg.DE shouldBe 0xF83C
+    reg.D shouldBe 0xF8
+    reg.E shouldBe 0x3C
+
+    reg.HL = 0xF83C
+    reg.HL shouldBe 0xF83C
+    reg.H shouldBe 0xF8
+    reg.L shouldBe 0x3C
+
+  }
+
+  "Test 8-Bit register validation" {
+    val reg = Registers()
+    shouldThrow<IllegalArgumentException> {
+      reg.A = 0xFFFF
+      Any()
+    }
+    shouldThrow<IllegalArgumentException> {
+      reg.F = 0xFFFF
+      Any()
+    }
+    shouldThrow<IllegalArgumentException> {
+      reg.B = 0xFFFF
+      Any()
+    }
+    shouldThrow<IllegalArgumentException> {
+      reg.C = 0xFFFF
+      Any()
+    }
+    shouldThrow<IllegalArgumentException> {
+      reg.D = 0xFFFF
+      Any()
+    }
+    shouldThrow<IllegalArgumentException> {
+      reg.E = 0xFFFF
+      Any()
+    }
+    shouldThrow<IllegalArgumentException> {
+      reg.H = 0xFFFF
+      Any()
+    }
+    shouldThrow<IllegalArgumentException> {
+      reg.L = 0xFFFF
+      Any()
+    }
+  }
+
+  "Test 16-Bit register validation" {
+    val reg = Registers()
+    shouldThrow<IllegalArgumentException> {
+      reg.AF = 0xFFFFFF
+      Any()
+    }
+    shouldThrow<IllegalArgumentException> {
+      reg.BC = 0xFFFFFF
+      Any()
+    }
+    shouldThrow<IllegalArgumentException> {
+      reg.DE = 0xFFFFFF
+      Any()
+    }
+    shouldThrow<IllegalArgumentException> {
+      reg.HL = 0xFFFFFF
+      Any()
+    }
+    shouldThrow<IllegalArgumentException> {
+      reg.SP = 0xFFFFFF
+      Any()
+    }
+    shouldThrow<IllegalArgumentException> {
+      reg.PC = 0xFFFFFF
+      Any()
+    }
+
+  }
+
+  "Test registers" {
+    val reg = Registers()
+
+    reg.A = 0xA0
+    reg.A shouldBe 0xA0
+    reg.F = 0xA1
+    reg.F shouldBe 0xA1
+
+    reg.B = 0xA2
+    reg.B shouldBe 0xA2
+    reg.C = 0xA3
+    reg.C shouldBe 0xA3
+    reg.D = 0xA4
+    reg.D shouldBe 0xA4
+    reg.E = 0xA5
+    reg.E shouldBe 0xA5
+    reg.H = 0xA6
+    reg.H shouldBe 0xA6
+    reg.L = 0xA7
+    reg.L shouldBe 0xA7
+
+    reg.SP = 0xAAFE
+    reg.SP shouldBe 0xAAFE
+
+    reg.PC = 0xAAFE
+    reg.PC shouldBe 0xAAFE
+  }
+
+})
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