C64-dev/vim/to-petscii.ps1

# to-petscii.ps1 - convert an ASCII C source file into the PETSCII form
# Power C expects on a C64 disk: uppercase letters shifted into $C1-$DA,
# lowercase into $41-$5A, { } into $DB/$DD, and CR ($0D) line endings.
#
# Usage:
#   powershell -NoProfile -File to-petscii.ps1 vim.c vim.pet

param(
    [Parameter(Mandatory = $true)][string]$InFile,
    [Parameter(Mandatory = $true)][string]$OutFile
)

$bytes = [System.IO.File]::ReadAllBytes($InFile)
$start = 0
if ($bytes.Length -ge 3 -and $bytes[0] -eq 0xEF -and $bytes[1] -eq 0xBB -and $bytes[2] -eq 0xBF) {
    $start = 3                       # skip a UTF-8 BOM if an editor added one
}

$out = New-Object System.Collections.Generic.List[byte]
for ($i = $start; $i -lt $bytes.Length; $i++) {
    $b = $bytes[$i]
    if ($b -eq 13) { continue }                              # CRLF -> single CR
    if ($b -eq 10) { $out.Add([byte]13); continue }
    if ($b -ge 0x61 -and $b -le 0x7A) { $out.Add([byte]($b - 0x20)); continue }   # a-z
    if ($b -ge 0x41 -and $b -le 0x5A) { $out.Add([byte]($b + 0x80)); continue }   # A-Z
    if ($b -ge 0x7B -and $b -le 0x7F) { $out.Add([byte]($b + 0x60)); continue }   # { | } ~ -> $DB-$DF
    $out.Add([byte]$b)
}

[System.IO.File]::WriteAllBytes($OutFile, $out.ToArray())
Write-Host ("wrote {0} PETSCII bytes to {1}" -f $out.Count, $OutFile)