#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
merge_image.py - Merge the CAIIC bootloader and application binaries into a
                 single flash package for N32WB031KEQ6-2 (512KB).

Inputs (produced by the Keil after-build fromelf step):
    Boot/MDK-ARM/bin/caiic_boot.bin        -> 0x01000000
    mcm-ddc-04/MDK-ARM/bin/embeddedSrc.bin -> 0x01008000 (APP1 bank)

Outputs (written to tools/out/):
    caiic_full.hex   Intel HEX, sparse (gaps omitted) - for pyocd/NSpyocd/J-Flash
    caiic_full.bin   raw binary from 0x01000000, gaps padded with 0xFF

Usage:  python tools/merge_image.py
Run from anywhere; paths are resolved relative to this script.
"""
import os
import sys

FLASH_BASE = 0x01000000

# (input bin relative to repo root, load address)
IMAGES = [
    (os.path.join("Boot", "MDK-ARM", "bin", "caiic_boot.bin"),      0x01000000),
    (os.path.join("mcm-ddc-04", "MDK-ARM", "bin", "embeddedSrc.bin"), 0x01008000),
]

OUT_DIR = "out"
HEX_NAME = "caiic_full.hex"
BIN_NAME = "caiic_full.bin"

HEX_REC_LEN = 16


def hex_record(addr, rectype, data):
    """Build one Intel HEX record string."""
    body = [len(data), (addr >> 8) & 0xFF, addr & 0xFF, rectype] + list(data)
    cks = (-sum(body)) & 0xFF
    return ":" + "".join("%02X" % b for b in body) + "%02X" % cks + "\n"


def write_hex(path, segments):
    """Write segments [(base_addr, bytes)] as Intel HEX with ELA records."""
    with open(path, "w") as f:
        ela = None
        for base, blob in segments:
            for off in range(0, len(blob), HEX_REC_LEN):
                addr = base + off
                new_ela = addr >> 16
                if new_ela != ela:
                    ela = new_ela
                    f.write(hex_record(0, 4, [(ela >> 8) & 0xFF, ela & 0xFF]))
                f.write(hex_record(addr & 0xFFFF, 0, blob[off:off + HEX_REC_LEN]))
        f.write(":00000001FF\n")


def main():
    root = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
    segments = []
    for rel, addr in IMAGES:
        path = os.path.join(root, rel)
        if not os.path.isfile(path):
            print("ERROR: %s not found - build the Keil project first" % rel)
            return 1
        with open(path, "rb") as f:
            blob = f.read()
        segments.append((addr, blob))
        print("%-46s -> 0x%08X  (%d bytes)" % (rel, addr, len(blob)))

    out_dir = os.path.join(root, "tools", OUT_DIR)
    if not os.path.isdir(out_dir):
        os.makedirs(out_dir)

    hex_path = os.path.join(out_dir, HEX_NAME)
    write_hex(hex_path, segments)

    # merged bin: FLASH_BASE .. end of last segment, gaps padded with 0xFF
    end = max(addr + len(blob) for addr, blob in segments)
    merged = bytearray(b"\xFF" * (end - FLASH_BASE))
    for addr, blob in segments:
        merged[addr - FLASH_BASE: addr - FLASH_BASE + len(blob)] = blob
    bin_path = os.path.join(out_dir, BIN_NAME)
    with open(bin_path, "wb") as f:
        f.write(bytes(merged))

    print("")
    print("package written:")
    print("  %s" % hex_path)
    print("  %s  (base 0x%08X, %d bytes)" % (bin_path, FLASH_BASE, len(merged)))
    return 0


if __name__ == "__main__":
    sys.exit(main())