59 lines
1.2 KiB
Go
59 lines
1.2 KiB
Go
package apple2
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type memoryRange struct {
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base uint16
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data []uint8
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basePtr uintptr
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}
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type memoryRangeROM struct {
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memoryRange
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}
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func newMemoryRange(base uint16, data []uint8) *memoryRange {
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var m memoryRange
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m.base = base
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m.data = data
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m.setBase(base)
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return &m
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}
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func newMemoryRangeROM(base uint16, data []uint8) *memoryRangeROM {
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var m memoryRangeROM
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m.base = base
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m.data = data
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m.setBase(base)
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return &m
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}
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func (m *memoryRange) setBase(base uint16) {
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m.base = base
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//p := unsafe.Pointer(&m.data[0])
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//m.basePtr = (uintptr)(p) - (uintptr)(base)
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}
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func (m *memoryRange) peek(address uint16) uint8 {
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// Safe version:
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return m.data[address-m.base]
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// Really overkill
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// go-vet warns the caching of basePtr
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// This wouldn't have a warning
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// indexp := unsafe.Pointer((uintptr)(unsafe.Pointer(&m.data[0])) - (uintptr)(m.base) + uintptr(address))
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// But it makes sense to precalculate that
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//indexp := unsafe.Pointer(m.basePtr + uintptr(address))
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//return *(*uint8)(indexp)
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}
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func (m *memoryRange) poke(address uint16, value uint8) {
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m.data[address-m.base] = value
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}
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func (m *memoryRange) subRange(a, b uint16) []uint8 {
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return m.data[a-m.base : b-m.base]
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}
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func (m *memoryRangeROM) poke(address uint16, value uint8) {
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// Ignore
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}
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