48 lines
1.1 KiB
Go
48 lines
1.1 KiB
Go
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package riscvemu
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type VirtualEEI struct {
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Ram []byte
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}
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func (ve *VirtualEEI) ReadByte(addr uint32) (byte, error) {
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if addr >= uint32(len(ve.Ram)) {
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panic("out of bounds")
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}
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return ve.Ram[addr], nil
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}
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func (ve *VirtualEEI) Read32(addr uint32) (uint32, error) {
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// n.b. will panic on overflow
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// RISC-V allows 32-bit load/stores to be implemented as either little-endian
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// or big-endian. This is the little-endian version
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return (uint32(ve.Ram[addr]) << 24) | (uint32(ve.Ram[addr+1]) << 16) | (uint32(ve.Ram[addr+2]) << 8) | uint32(ve.Ram[addr+3]), nil
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}
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func (ve *VirtualEEI) WriteByte(addr uint32, value byte) error {
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if addr >= uint32(len(ve.Ram)) {
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panic("out of bounds")
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}
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ve.Ram[addr] = value
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return nil
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}
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func (ve *VirtualEEI) Write32(addr, value uint32) error {
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// n.b. will panic on overflow
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ve.Ram[addr] = byte((value >> 24) & 0b11111111)
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ve.Ram[addr+1] = byte((value >> 16) & 0b11111111)
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ve.Ram[addr+2] = byte((value >> 8) & 0b11111111)
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ve.Ram[addr+3] = byte(value & 0b11111111)
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return nil
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}
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func (ve *VirtualEEI) Syscall() {
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panic("syscall")
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}
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func (ve *VirtualEEI) Trap() (bool, error) {
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panic("trap")
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}
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