set script_dir [file dirname [file normalize [info script]]]
set fpga_dir [file normalize [file join $script_dir ../..]]

proc getenv_default {name default} {
  if {[info exists ::env($name)] && $::env($name) ne ""} {
    return $::env($name)
  }
  return $default
}

proc region_end {offset file} {
  return [expr {$offset + [file size $file]}]
}

set bit_file [file normalize [getenv_default BIT_FILE [file join $fpga_dir out bitstream genesys2_rocket.bit]]]
set app_image [file normalize [getenv_default APP_FLASH_IMAGE [file join $fpga_dir out flash hello_uart.flash.bin]]]
set bitstream_mcs [file normalize [getenv_default BITSTREAM_MCS [file join $fpga_dir out flash regions bitstream.mcs]]]
set app_mcs [file normalize [getenv_default APP_MCS [file join $fpga_dir out flash regions app.mcs]]]
set flash_size_mb [getenv_default FLASH_SIZE_MB 32]
set flash_interface [getenv_default FLASH_INTERFACE SPIx4]
set bitstream_offset [getenv_default BITSTREAM_OFFSET 0x00000000]
set app_flash_offset [getenv_default APP_FLASH_OFFSET 0x01800000]
set assistance_flash_offset [getenv_default ASSISTANCE_FLASH_OFFSET 0x01f80000]
set assistance_flash_size [getenv_default ASSISTANCE_FLASH_SIZE 0x00080000]
set region_names [split [getenv_default FLASH_REGION_NAMES "bitstream;app"] ";"]
set flash_size_bytes [expr {$flash_size_mb * 1024 * 1024}]
set assistance_end [expr {$assistance_flash_offset + $assistance_flash_size}]
if {$assistance_end > $flash_size_bytes} {
  error [format "GPS assistance reservation exceeds flash: end=0x%08x flash_size=0x%08x" $assistance_end $flash_size_bytes]
}

foreach region $region_names {
  if {$region eq ""} {
    continue
  } elseif {$region eq "bitstream"} {
    if {![file exists $bit_file]} {
      error "Bitstream not found: $bit_file"
    }
    set bitstream_end [region_end $bitstream_offset $bit_file]
    if {$bitstream_end > $flash_size_bytes} {
      error [format "Bitstream region exceeds flash: end=0x%08x flash_size=0x%08x" $bitstream_end $flash_size_bytes]
    }
    if {$bitstream_end > $app_flash_offset} {
      error [format "Bitstream region crosses APP_FLASH_OFFSET: bit_end=0x%08x app_offset=0x%08x" \
        $bitstream_end $app_flash_offset]
    }
    if {$bitstream_offset < $assistance_end && $assistance_flash_offset < $bitstream_end} {
      error [format "Bitstream overlaps GPS assistance reservation: bit=[0x%08x,0x%08x) assistance=[0x%08x,0x%08x)" \
        $bitstream_offset $bitstream_end $assistance_flash_offset $assistance_end]
    }
    file mkdir [file dirname $bitstream_mcs]
    puts "Generating bitstream region MCS:"
    puts "  bitstream: $bit_file @ $bitstream_offset"
    puts [format "  flash size: 0x%08x bytes" $flash_size_bytes]
    puts [format "  bitstream end: 0x%08x" $bitstream_end]
    write_cfgmem -force -format MCS -size $flash_size_mb -interface $flash_interface \
      -loadbit "up $bitstream_offset $bit_file" \
      $bitstream_mcs
    puts "Wrote $bitstream_mcs"
  } elseif {$region eq "app"} {
    if {![file exists $app_image]} {
      error "Application flash image not found: $app_image"
    }
    set app_end [region_end $app_flash_offset $app_image]
    if {$app_end > $flash_size_bytes} {
      error [format "App region exceeds flash: end=0x%08x flash_size=0x%08x" $app_end $flash_size_bytes]
    }
    if {$app_flash_offset < $assistance_end && $assistance_flash_offset < $app_end} {
      error [format "App overlaps GPS assistance reservation: app=[0x%08x,0x%08x) assistance=[0x%08x,0x%08x)" \
        $app_flash_offset $app_end $assistance_flash_offset $assistance_end]
    }
    file mkdir [file dirname $app_mcs]
    puts "Generating app region MCS:"
    puts "  app image: $app_image @ $app_flash_offset"
    puts [format "  flash size: 0x%08x bytes" $flash_size_bytes]
    puts [format "  app end: 0x%08x" $app_end]
    write_cfgmem -force -format MCS -size $flash_size_mb -interface $flash_interface \
      -loaddata "up $app_flash_offset $app_image" \
      $app_mcs
    puts "Wrote $app_mcs"
  } else {
    error "Unknown flash region: $region"
  }
}