mirror of
https://github.com/ivanizag/izapple2.git
synced 2024-10-31 20:09:02 +00:00
165 lines
3.0 KiB
Go
165 lines
3.0 KiB
Go
package apple2
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import (
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"encoding/binary"
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"io"
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)
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/*
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RAM card with 128Kb. It's like 8 language cards.
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http://www.applelogic.org/files/SATURN128MAN.pdf
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*/
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type cardSaturn struct {
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cardBase
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readState bool
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writeState uint8
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altBank bool
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activeBlock uint8
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}
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const (
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saturnBlocks = 8
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)
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func (c *cardSaturn) assign(a *Apple2, slot int) {
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c.readState = false
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c.writeState = lcWriteEnabled
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c.altBank = true
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c.activeBlock = 0
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a.mmu.initLanguageRAM(saturnBlocks)
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for i := uint8(0x0); i <= 0xf; i++ {
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iCopy := i
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c.addCardSoftSwitchR(iCopy, func(*ioC0Page) uint8 {
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c.ssAction(iCopy)
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return 0
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}, "SATURNR")
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c.addCardSoftSwitchW(iCopy, func(*ioC0Page, uint8) {
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c.ssAction(iCopy)
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}, "SATURNW")
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}
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c.cardBase.assign(a, slot)
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c.applyState()
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}
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func (c *cardSaturn) ssAction(ss uint8) {
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switch ss {
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case 0:
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// RAM read, no writes
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c.altBank = false
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c.readState = true
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c.writeState = lcWriteDisabled
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case 1:
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// ROM read, RAM write
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c.altBank = false
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c.readState = false
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c.writeState++
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case 2:
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// ROM read, no writes
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c.altBank = false
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c.readState = false
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c.writeState = lcWriteDisabled
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case 3:
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//RAM read, RAM write
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c.altBank = false
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c.readState = true
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c.writeState++
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case 4:
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c.activeBlock = 0
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case 5:
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c.activeBlock = 1
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case 6:
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c.activeBlock = 2
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case 7:
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c.activeBlock = 3
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case 8:
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// RAM read, no writes
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c.altBank = true
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c.readState = true
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c.writeState = lcWriteDisabled
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case 9:
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// ROM read, RAM write
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c.altBank = true
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c.readState = false
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c.writeState++
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case 10:
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// ROM read, no writes
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c.altBank = true
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c.readState = false
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c.writeState = lcWriteDisabled
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case 11:
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//RAM read, RAM write
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c.altBank = true
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c.readState = true
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c.writeState++
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case 12:
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c.activeBlock = 4
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case 13:
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c.activeBlock = 5
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case 14:
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c.activeBlock = 6
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case 15:
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c.activeBlock = 7
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}
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if c.writeState > lcWriteEnabled {
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c.writeState = lcWriteEnabled
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}
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c.applyState()
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}
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func (c *cardSaturn) applyState() {
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c.a.mmu.setLanguageRAMActiveBlock(c.activeBlock)
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c.a.mmu.setLanguageRAM(c.readState, c.writeState == lcWriteEnabled, c.altBank)
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}
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func (c *cardSaturn) save(w io.Writer) error {
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for i := 0; i < saturnBlocks; i++ {
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err := binary.Write(w, binary.BigEndian, c.readState)
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if err != nil {
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return err
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}
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err = binary.Write(w, binary.BigEndian, c.writeState)
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if err != nil {
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return err
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}
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err = binary.Write(w, binary.BigEndian, c.altBank)
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if err != nil {
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return err
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}
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err = binary.Write(w, binary.BigEndian, c.activeBlock)
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if err != nil {
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return err
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}
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}
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return c.cardBase.save(w)
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}
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func (c *cardSaturn) load(r io.Reader) error {
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for i := 0; i < saturnBlocks; i++ {
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err := binary.Read(r, binary.BigEndian, &c.readState)
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if err != nil {
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return err
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}
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err = binary.Read(r, binary.BigEndian, &c.writeState)
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if err != nil {
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return err
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}
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err = binary.Read(r, binary.BigEndian, &c.altBank)
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if err != nil {
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return err
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}
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err = binary.Read(r, binary.BigEndian, &c.activeBlock)
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if err != nil {
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return err
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}
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c.applyState()
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}
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return c.cardBase.load(r)
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}
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