73 lines
1.6 KiB
Go
73 lines
1.6 KiB
Go
package compiler
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import (
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"fmt"
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)
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// MakeInstruction returns a bytecode for an opcode and the operands.
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func MakeInstruction(opcode Opcode, operands ...int) []byte {
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numOperands := OpcodeOperands[opcode]
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totalLen := 1
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for _, w := range numOperands {
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totalLen += w
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}
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instruction := make([]byte, totalLen)
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instruction[0] = byte(opcode)
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offset := 1
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for i, o := range operands {
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width := numOperands[i]
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switch width {
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case 1:
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instruction[offset] = byte(o)
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case 2:
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n := uint16(o)
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instruction[offset] = byte(n >> 8)
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instruction[offset+1] = byte(n)
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}
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offset += width
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}
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return instruction
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}
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// FormatInstructions returns string representation of
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// bytecode instructions.
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func FormatInstructions(b []byte, posOffset int) []string {
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var out []string
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i := 0
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for i < len(b) {
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numOperands := OpcodeOperands[Opcode(b[i])]
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operands, read := ReadOperands(numOperands, b[i+1:])
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switch len(numOperands) {
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case 0:
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out = append(out, fmt.Sprintf("%04d %-7s", posOffset+i, OpcodeNames[Opcode(b[i])]))
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case 1:
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out = append(out, fmt.Sprintf("%04d %-7s %-5d", posOffset+i, OpcodeNames[Opcode(b[i])], operands[0]))
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case 2:
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out = append(out, fmt.Sprintf("%04d %-7s %-5d %-5d", posOffset+i, OpcodeNames[Opcode(b[i])], operands[0], operands[1]))
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}
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i += 1 + read
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}
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return out
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}
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func iterateInstructions(b []byte, fn func(pos int, opcode Opcode, operands []int) bool) {
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for i := 0; i < len(b); i++ {
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numOperands := OpcodeOperands[Opcode(b[i])]
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operands, read := ReadOperands(numOperands, b[i+1:])
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if !fn(i, b[i], operands) {
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break
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}
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i += read
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}
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}
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