From a144937e244bacf5260d6bc6daaeab6e4008d4b3 Mon Sep 17 00:00:00 2001
From: XeonSquared <redtailedairways@gmail.com>
Date: Sat, 5 Aug 2023 10:19:07 +1000
Subject: [PATCH] implement proper tape support, also speed up loading from
 tapes.

---
 partition/driveboot.lua | 39 ++++++++++++++++++++++-----------------
 1 file changed, 22 insertions(+), 17 deletions(-)

diff --git a/partition/driveboot.lua b/partition/driveboot.lua
index 20c7b10..56341c5 100644
--- a/partition/driveboot.lua
+++ b/partition/driveboot.lua
@@ -1,10 +1,11 @@
+return (function()
+local component = component
 function computer.getBootAddress()
  return component.invoke(component.list("eeprom")(),"getData")
 end
 function computer.setBootAddress(a)
  return component.invoke(component.list("eeprom")(),"setData",a)
 end
-return (function()
 local rv
 local function getProxy(addr)
  if type(addr) == "string" then
@@ -13,14 +14,22 @@ local function getProxy(addr)
  return addr
 end
 local function aop(td,n,mn,...)
- local rts = td.seek(-math.huge)
- td.seek(n)
- local rv = {td[mn](...)}
- td.seek(-math.huge)
- td.seek(rts)
+ local rv
+ if td.getPosition then
+  local rts = td.getPosition()
+  if rts ~= n then
+   td.seek(n - rts)
+  end
+  rv = {td[mn](...)}
+ else
+  local rts = td.seek(-math.huge)
+  td.seek(n)
+  rv = {td[mn](...)}
+  td.seek(-math.huge)
+  td.seek(rts)
+ end
  return table.unpack(rv)
 end
-
 local eformat = "c20c4>I4>I4"
 function parsePartitions(s)
  local rt = {}
@@ -33,7 +42,6 @@ function parsePartitions(s)
  end
  return rt
 end
-
 function getPartitions(drive)
  local rv
  if drive.type == "tape_drive" then
@@ -45,7 +53,6 @@ function getPartitions(drive)
  end
  return rv[1][2] == "mtpt" and rv
 end
-
 local function offsetSector(part,sector)
  if sector < 1 or sector > part[4] then error("invalid offset, not in a usable sector") end
  return (part[3] - 1) + sector
@@ -54,16 +61,16 @@ local function readSector(drive,part,sector)
  return drive.readSector(offsetSector(part,sector)):gsub("\0+$","")
 end
 local function readPart(drive,part)
- if drive.type == "tape_drive" then
-  return aop(drive, (part[3]-1)*512, "read", part[4] * 512)
- end
  local rv = ""
  for i = 1, part[4] do
-  rv=rv .. readSector(drive,part,i)
+  if drive.type == "tape_drive" then
+   rv=rv .. aop(drive, ((part[3]-2) + i)*512, "read", 512):gsub("\0+$","")
+  else
+   rv=rv .. readSector(drive,part,i)
+  end
  end
  return rv
 end
-
 local pB = computer.getBootAddress()
 local candidates={pB,[pB] = true}
 if not component.type(pB) then candidates[1] = nil end
@@ -71,11 +78,10 @@ for a,t in component.list() do
  candidates[#candidates+1] = not candidates[a] and (t == "drive" or t == "filesystem" or t == "tape_drive") and a or nil
  candidates[a] = true
 end
-
 local function wL()
  return false
 end
-local cL = wL
+local cL=wL
 local ga, sa = component.list("gpu")(), component.list("screen")()
 if ga and sa then
  local g, cl = component.proxy(ga), 1
@@ -110,7 +116,6 @@ if ga and sa then
   end
  until computer.uptime() >= to
 end
-
 for i,a in ipairs(candidates) do
  computer.beep(("."):rep(i))
  wL("Attempting to load from "..a)