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reader.go
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reader.go
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package z80
import (
"fmt"
"strings"
"github.com/blackchip-org/retro-cs/rcs"
)
func Reader(e rcs.StmtEval) {
e.Stmt.Addr = e.Ptr.Addr()
opcode := e.Ptr.Fetch()
e.Stmt.Bytes = []uint8{opcode}
dasmTable[opcode](e)
}
func Formatter() rcs.CodeFormatter {
options := rcs.FormatOptions{
BytesFormat: "%-11s",
}
return func(s rcs.Stmt) string {
return rcs.FormatStmt(s, options)
}
}
func NewDisassembler(mem *rcs.Memory) *rcs.Disassembler {
return rcs.NewDisassembler(mem, Reader, Formatter())
}
func op1(e rcs.StmtEval, parts ...string) {
var out strings.Builder
for i, part := range parts {
v := part
switch {
case i == 0:
v = fmt.Sprintf("%-4s", part)
case parts[0] == "rst" && i == 1:
// Reset statements have the argment encoded in the opcode. Change
// the hex notation from & to $ in the second part
v = "$" + v[1:]
case part == "&4546":
// This is an address that is a 8-bit displacement from the
// current program counter
delta := e.Ptr.Fetch()
e.Stmt.Bytes = append(e.Stmt.Bytes, delta)
addr := displace(e.Stmt.Addr+2, delta)
v = fmt.Sprintf("$%04x", addr)
case part == "&0000":
lo := e.Ptr.Fetch()
e.Stmt.Bytes = append(e.Stmt.Bytes, lo)
hi := e.Ptr.Fetch()
e.Stmt.Bytes = append(e.Stmt.Bytes, hi)
addr := int(hi)<<8 | int(lo)
v = fmt.Sprintf("$%04x", addr)
case part == "(&0000)":
lo := e.Ptr.Fetch()
e.Stmt.Bytes = append(e.Stmt.Bytes, lo)
hi := e.Ptr.Fetch()
e.Stmt.Bytes = append(e.Stmt.Bytes, hi)
addr := int(hi)<<8 | int(lo)
v = fmt.Sprintf("($%04x)", addr)
case part == "&00":
arg := e.Ptr.Fetch()
e.Stmt.Bytes = append(e.Stmt.Bytes, arg)
v = fmt.Sprintf("$%02x", arg)
case part == "(&00)":
arg := e.Ptr.Fetch()
e.Stmt.Bytes = append(e.Stmt.Bytes, arg)
v = fmt.Sprintf("($%02x)", arg)
case part == "(ix+0)":
delta := e.Ptr.Fetch()
e.Stmt.Bytes = append(e.Stmt.Bytes, delta)
v = fmt.Sprintf("(ix+$%02x)", delta)
case part == "(iy+0)":
delta := e.Ptr.Fetch()
e.Stmt.Bytes = append(e.Stmt.Bytes, delta)
v = fmt.Sprintf("(iy+$%02x)", delta)
}
if i == 1 {
out.WriteString(" ")
}
if i == 2 {
out.WriteString(",")
}
out.WriteString(v)
}
e.Stmt.Op = strings.TrimSpace(out.String())
}
func op2(e rcs.StmtEval, parts ...string) {
var out strings.Builder
for i, part := range parts {
v := part
switch {
case i == 0:
v = fmt.Sprintf("%-4s", part)
case part == "(ix+0)":
delta := e.Stmt.Bytes[len(e.Stmt.Bytes)-2]
v = fmt.Sprintf("(ix+$%02x)", delta)
case part == "(iy+0)":
delta := e.Stmt.Bytes[len(e.Stmt.Bytes)-2]
v = fmt.Sprintf("(iy+$%02x)", delta)
}
if i == 1 {
out.WriteString(" ")
}
if i == 2 {
out.WriteString(",")
}
out.WriteString(v)
}
e.Stmt.Op = strings.TrimSpace(out.String())
}
func opDD(e rcs.StmtEval) {
next := e.Ptr.Peek()
if next == 0xdd || next == 0xed || next == 0xfd {
e.Stmt.Op = "?dd"
return
}
opcode := e.Ptr.Fetch()
e.Stmt.Bytes = append(e.Stmt.Bytes, opcode)
if opcode == 0xcb {
opDDCB(e)
return
}
dasmTableDD[opcode](e)
}
func opFD(e rcs.StmtEval) {
next := e.Ptr.Peek()
if next == 0xdd || next == 0xed || next == 0xfd {
e.Stmt.Op = "?fd"
return
}
opcode := e.Ptr.Fetch()
e.Stmt.Bytes = append(e.Stmt.Bytes, opcode)
if opcode == 0xcb {
opFDCB(e)
return
}
dasmTableFD[opcode](e)
}
func opCB(e rcs.StmtEval) {
opcode := e.Ptr.Fetch()
e.Stmt.Bytes = append(e.Stmt.Bytes, opcode)
dasmTableCB[opcode](e)
}
func opED(e rcs.StmtEval) {
opcode := e.Ptr.Fetch()
e.Stmt.Bytes = append(e.Stmt.Bytes, opcode)
dasmTableED[opcode](e)
}
func opFDCB(e rcs.StmtEval) {
delta := e.Ptr.Fetch()
e.Stmt.Bytes = append(e.Stmt.Bytes, delta)
opcode := e.Ptr.Fetch()
e.Stmt.Bytes = append(e.Stmt.Bytes, opcode)
dasmTableFDCB[opcode](e)
}
func opDDCB(e rcs.StmtEval) {
delta := e.Ptr.Fetch()
e.Stmt.Bytes = append(e.Stmt.Bytes, delta)
opcode := e.Ptr.Fetch()
e.Stmt.Bytes = append(e.Stmt.Bytes, opcode)
dasmTableDDCB[opcode](e)
}
func displace(value int, delta uint8) uint16 {
sdelta := int8(delta)
v := int(value) + int(sdelta)
return uint16(v)
}