# E01-S02: build the isolated C128 MMU/common-RAM proof.
[CmdletBinding()]
param()

$ErrorActionPreference = "Stop"
$project = Split-Path $PSScriptRoot -Parent
$build = Join-Path $project "build"
$source = Join-Path $project "src\platform\mmu-probe.s"
$config = Join-Path $project "cfg\mmu-probe-c128.cfg"
$object = Join-Path $build "mmu-probe.o"
$program = Join-Path $build "mmu-probe.prg"
$map = Join-Path $build "mmu-probe.map"
$labels = Join-Path $build "mmu-probe.lbl"
$debug = Join-Path $build "mmu-probe.dbg"
$listing = Join-Path $build "mmu-probe.lst"

$ca65 = (Get-Command ca65 -ErrorAction Stop).Source
$ld65 = (Get-Command ld65 -ErrorAction Stop).Source
New-Item -ItemType Directory -Force -Path $build | Out-Null

foreach ($path in @($object, $program, $map, $labels, $debug, $listing)) {
    if (Test-Path -LiteralPath $path) { Remove-Item -LiteralPath $path -Force }
}

& $ca65 --cpu 6502 --debug-info -l $listing -o $object $source
if ($LASTEXITCODE -ne 0) { throw "ca65 failed with exit code $LASTEXITCODE" }
& $ld65 -C $config -o $program -m $map -Ln $labels --dbgfile $debug $object
if ($LASTEXITCODE -ne 0) { throw "ld65 failed with exit code $LASTEXITCODE" }

$bytes = [IO.File]::ReadAllBytes($program)
if ($bytes.Length -lt 16) { throw "mmu-probe.prg is unexpectedly short" }
if ($bytes[0] -ne 0x01 -or $bytes[1] -ne 0x1C) {
    throw "mmu-probe.prg load address is not `$1C01"
}
$expectedHeader = [byte[]](0x0B,0x1C,0x0A,0x00,0x9E,0x37,0x31,0x38,0x31,0x00,0x00,0x00)
for ($i = 0; $i -lt $expectedHeader.Length; $i++) {
    if ($bytes[$i + 2] -ne $expectedHeader[$i]) {
        throw ("BASIC header differs at file offset {0}" -f ($i + 2))
    }
}

# The last loaded byte must remain below $2000, the end of the selected 8K
# bottom-common window. File bytes after the two-byte load address begin $1C01.
$lastAddress = 0x1C01 + ($bytes.Length - 2) - 1
if ($lastAddress -ge 0x2000) {
    throw ("probe ends at `${0:X4}, outside bottom common RAM" -f $lastAddress)
}

$labelText = Get-Content -Raw -LiteralPath $labels
foreach ($name in @(
    'mmu_probe_entry','mmu_probe_done','mmu_probe_result','mmu_probe_complete',
    'mmu_probe_observed_bank0','mmu_probe_observed_bank1',
    'mmu_probe_observed_p0','mmu_probe_observed_p1')) {
    if ($labelText -notmatch ("(?im)^al\s+[0-9a-f]+\s+\." + [regex]::Escape($name) + "\s*$")) {
        throw "missing exported linker label $name"
    }
}

Write-Host ("built {0} ({1} bytes, ends `${2:X4})" -f $program, $bytes.Length, $lastAddress)
Write-Host ("map   {0}" -f $map)
Write-Host ("labels {0}" -f $labels)