ksim65/src/main/kotlin/razorvine/ksim65/components/Rom.kt

package razorvine.ksim65.components

import java.io.File

/**
 * A ROM chip (read-only memory).
 */
class Rom(startAddress: Address, endAddress: Address, initialData: Array<UByte>? = null) : MemoryComponent(startAddress, endAddress) {
    override val data: Array<UByte> = initialData?.copyOf() ?: Array(endAddress-startAddress+1) { 0 }

    init {
        require(endAddress-startAddress+1 == data.size) { "rom address range doesn't match size of data bytes" }
    }

    override operator fun get(offset: Int): UByte = data[offset]
    override operator fun set(offset: Int, data: UByte) { /* read-only */ }

    override fun clock() {}
    override fun reset() {}

    /**
     * load a binary program at the given address
     */
    fun load(filename: String) {
        val bytes = File(filename).readBytes()
        load(bytes)
    }

    fun load(data: Array<UByte>) = data.copyInto(this.data)

    fun load(data: ByteArray) = data.map { (it.toInt() and 255).toShort() }.toTypedArray().copyInto(this.data)
}