// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: BSD-3-Clause

//go:build freebsd && arm64

package debug

// Regs holds the full general-purpose register set of a traced process
// (the FreeBSD arm64 struct reg layout, sys/arm64/include/reg.h: x[30], lr,
// sp, elr, spsr).
type Regs struct {
	X0     uint64
	X1     uint64
	X2     uint64
	X3     uint64
	X4     uint64
	X5     uint64
	X6     uint64
	X7     uint64
	X8     uint64
	X9     uint64
	X10    uint64
	X11    uint64
	X12    uint64
	X13    uint64
	X14    uint64
	X15    uint64
	X16    uint64
	X17    uint64
	X18    uint64
	X19    uint64
	X20    uint64
	X21    uint64
	X22    uint64
	X23    uint64
	X24    uint64
	X25    uint64
	X26    uint64
	X27    uint64
	X28    uint64
	X29    uint64 // FP (frame pointer)
	X30    uint64 // LR (link register)
	SP     uint64
	PC     uint64
	PSTATE uint64
}

// GetPC returns the program counter.
func (r *Regs) GetPC() uint64 { return r.PC }

// SetPC sets the program counter.
func (r *Regs) SetPC(pc uint64) { r.PC = pc }

// GetSP returns the stack pointer.
func (r *Regs) GetSP() uint64 { return r.SP }

// RegValue returns the value of the named register, or false if unknown.
func (r *Regs) RegValue(name string) (uint64, bool) {
	switch name {
	case "x0":
		return r.X0, true
	case "x1":
		return r.X1, true
	case "x2":
		return r.X2, true
	case "x3":
		return r.X3, true
	case "x4":
		return r.X4, true
	case "x5":
		return r.X5, true
	case "x6":
		return r.X6, true
	case "x7":
		return r.X7, true
	case "x8":
		return r.X8, true
	case "x9":
		return r.X9, true
	case "x10":
		return r.X10, true
	case "x11":
		return r.X11, true
	case "x12":
		return r.X12, true
	case "x13":
		return r.X13, true
	case "x14":
		return r.X14, true
	case "x15":
		return r.X15, true
	case "x16":
		return r.X16, true
	case "x17":
		return r.X17, true
	case "x18":
		return r.X18, true
	case "x19":
		return r.X19, true
	case "x20":
		return r.X20, true
	case "x21":
		return r.X21, true
	case "x22":
		return r.X22, true
	case "x23":
		return r.X23, true
	case "x24":
		return r.X24, true
	case "x25":
		return r.X25, true
	case "x26":
		return r.X26, true
	case "x27":
		return r.X27, true
	case "x28":
		return r.X28, true
	case "x29", "fp":
		return r.X29, true
	case "x30", "lr":
		return r.X30, true
	case "sp":
		return r.SP, true
	case "pc":
		return r.PC, true
	default:
		return 0, false
	}
}

// breakpointInsn is the software breakpoint instruction (BRK #0).
var breakpointInsn = []byte{0x00, 0x00, 0x20, 0xD4} // BRK #0

// breakpointPCAdjust is how far PC is past the breakpoint instruction after
// a trap: 0.  The BRK synchronous exception leaves ELR_EL0 on the BRK
// itself (ARM DDI 0487), and the FreeBSD EXCP_BRKPT_EL0 handler delivers
// the frame's elr unmodified (sys/arm64/arm64/trap.c), so the trap address
// is the PC as reported.
const breakpointPCAdjust = 0