//R E A D O P S
//functions for ReadPress
// Copyright Xerox Corporation 1979

//outgoing routines
external [
ReadPart;ReadEntity;ReadObject;ReadFont
]

//incoming routines
external [
DoubleShr;DoubleCop;DoubleSub;MulFull
GetByte;GetWord;OddByte;GetReset
ShowFloat;Show;Shown;Showch;Error;DLEven//from readpress

ReadBlock//OS
Gets
SetFilePos
FilePos
DoubleAdd
Usc
]

//incoming statics
external [
PressFile
]

//internal manifest and structure declarations
structure str:
[
n byte
ch↑1,255 byte
]

structure
[
lhbyte
rhbyte
]

let ReadPart(n) be
[
let PartDir=vec 4
for i=1 to n do ReadBlock(PressFile,PartDir,4)

let Type=PartDir!0
let Start=PartDir!1
let Len=PartDir!2
let padding=PartDir!3

Show("*nPart ");Shown(n)
Show(":*n Type=")
switchon Type into
[
case 0: Show("Page*n");endcase
case 1: Show("Font*n");endcase
case 2: Show("External File Directory*n");endcase
default: Show("Unknown (");Shown(Type);Show(")*n");endcase
]
Show("*n Record Start=");Shown(Start)
Show("*n Length (in records)=");Shown(Len)
Show("*n Padding Length=");Shown(padding)

if Type eq 0 then //show commands
[
let dataPos=vec 1
MulFull(Start,512,dataPos)
let partPos=vec 1
MulFull(Len,512,partPos)
DoubleAdd(partPos,dataPos)
let doublePadding=vec 1
doublePadding!0=0;doublePadding!1=padding*2+2
DoubleSub(partPos,doublePadding)
SetFilePos(PressFile,partPos)
let entityLen=Gets(PressFile)
until entityLen eq 0 do
entityLen=ReadEntity(entityLen,partPos,dataPos)
]

if Type eq 2 then //show files needed
[ let partPos=vec 1
MulFull(Start,512,partPos)
SetFilePos(PressFile,partPos)
let name=vec 40
ReadBlock(PressFile,name,1)
Show("*nFiles required:*n")
until name!0 eq 0 do
[ let wordLen=name>>str.n/2
ReadBlock(PressFile,name+1,wordLen)
Show(" ");Show(name);Show("*n")
ReadBlock(PressFile,name,1)
]
]


]

and ReadEntity(entityLen,partPos,dataPos)=valof
[
let evec=vec 1
evec!0=0
evec!1=entityLen
DoubleAdd(evec,evec)//*2 for byte position
DoubleSub(partPos,evec)
if partPos!0 ls 0 then
[
Show("*n ILLEGAL ENTITY LENGTH (=")
Shown(entityLen)
Show(")*n")
resultis 0
]
SetFilePos(PressFile,partPos)
let nextlen=Gets(PressFile)

let edata=@#335
@#335=edata+entityLen+1
if Usc(@#335, lv edata) gr 0 then
Error("Entity too long for READPRESS to read*n")

ReadBlock(PressFile,edata,entityLen)
let thisData=vec 1
DoubleCop(thisData,edata+entityLen-11)

Show("*nEntity: Length=");Shown(edata!(entityLen-1))
Show("*n Trailer:*n")
Show(" Type;Font=");Shown(edata!(entityLen-12))
Show("*n Begin-Byte=");Shown(thisData!0);
Showch($;);Shown(thisData!1)
Show(" Byte-Len=");Shown(edata!(entityLen-9))
Showch($;);Shown(edata!(entityLen-8))
Show("*n Xe=");Shown(edata!(entityLen-7))
Show(" Ye=");Shown(edata!(entityLen-6))
Show("*n left=");Shown(edata!(entityLen-5))
Show(" bottom=");Shown(edata!(entityLen-4))
Show("*n width=");Shown(edata!(entityLen-3))
Show(" height=");Shown(edata!(entityLen-2))

Show("*n Commands:*n")
let numBytes=(entityLen-12)*2
DoubleAdd(thisData,dataPos)
let oddByte=(thisData!1)&1
thisData!1=thisData!1𫙰//position to word boundary
SetFilePos(PressFile,thisData)
GetReset()
if oddByte then GetByte()
PrintCommands(numBytes,edata,thisData)

@#335=edata
resultis nextlen
]

and Grab(b,v)=valof
[
let n=@b
@b=n+1
let Word=v!(n/2)
resultis ((n&1) eq 1)?Word<<rh,Word<<lh
]

and GrabW(b,v) = Grab(b,v)*256+Grab(b,v)

and PrintCommands(numCommands,v,dataPos) be
[
let count=0
let pv=vec 10
let b=lv count

until count ge numCommands do
[//grab next byte
let c=Grab(b,v)
let p=1//num args, default is 1 arg
pv!1=Grab(b,v)//Get one argument ahead

let s=nil
switchon (cŲ)/#10 into
[
case 0: case 1: case 2: case 3: //show short
s="Show-Characters-Short"
pv!1=(c%)+1
count=count-1
c=#360
endcase
case 4: case 5: case 6: case 7://skip short
s="Skip-Characters-Short"
pv!1=(c%)+1
count=count-1
c=#361
endcase
case #10: case #11: case #12: case #13:
s="Show-Characters-and-Skip"
pv!1=(c%)+1
count=count-1
c=#100
endcase
case #14:
s="Set-Space-X-Short"
pv!1=(c)*256+pv!1
endcase
case #15:
s="Set-Space-Y-Short"
pv!1=(c&7)*256+pv!1
endcase
case #16:
case #17:
s="Font"
pv!1=c
count=count-1
endcase
default:
switchon c into
[
case #353: s="Skip-Control-Bytes-Immediate"
for i=1 to pv!1 do Grab(b,v)
endcase
case #354: s="Alternative"
pv!1=(pv!1)*256+Grab(b,v)//EL types
pv!2=GrabW(b,v)
pv!3=GrabW(b,v)
pv!4=GrabW(b,v)
pv!5=GrabW(b,v)
p=5;endcase
case #355: s="Only-on-copy";endcase
case #356: s="Set-X"
pv!1=(pv!1)*256+Grab(b,v);endcase
case #357: s="Set-Y"
pv!1=(pv!1)*256+Grab(b,v);endcase
case #360: s="Show-Characters";endcase
case #361: s="Skip-Characters";endcase
case #362: s="Skip-Control-Bytes"
pv!1=(pv!1)*256+Grab(b,v)
pv!2=Grab(b,v)//type
endcase
case #363: s="Show-Character-Immediate : "
s>>str.ch↑(s>>str.n-1)=pv!1
endcase
case #364: s="Set-Space-X"
pv!1=(pv!1)*256+Grab(b,v);endcase
case #365: s="Set-Space-Y"
pv!1=(pv!1)*256+Grab(b,v);endcase
case #366: s="Reset-Space";p=0;endcase
case #367: s="Space";p=0;endcase
case #370: s="Set-Brightness";endcase
case #371: s="Set-Hue";endcase
case #372: s="Set-Saturation";endcase
case #373: s="Show-Object"
pv!1=(pv!1)*256+Grab(b,v);endcase
case #374: s="Show-Dots"
pv!1=(pv!1)*256+Grab(b,v)
pv!2=GrabW(b,v);p=2;endcase
case #375: s="Show-Dots-Opaque"
pv!1=(pv!1)*256+Grab(b,v)
pv!2=GrabW(b,v);p=2;endcase
case #376: s="Show-Rectangle"
pv!1=(pv!1)*256+Grab(b,v)
pv!2=GrabW(b,v);p=2;endcase
case #377: s="Nop";p=0;endcase

default:
s=(c ge 200b & c le 237b)? "<..available..>","<..spare..>"
count=count-1
pv!1=c;endcase
]
]

//Now print out command name, and arguments:
Show(s)
test p eq 0 then count=count-1
or for i=1 to p do
[
Show(" ")
Shown(pv!i)
]
Show("*n")

//Now, if there’s any data in DL, show it
switchon c into
[
case #360: //Show Characters
Show(" ")
for i=1 to pv!1 do [ let ch=GetByte();Show(lv ch,1)]
Show("*N")
endcase
case #361: case #362://Skip Characters (or Control Bytes)
for i=1 to pv!1 do GetByte()
endcase
case #100: //Show Characters and Skip
Show(" ")
for i=1 to pv!1 do [ let ch=GetByte();Show(lv ch,1)]
Show("*N")
GetByte()
endcase
case #373: //Show Object
ReadObject(pv!1)
endcase
case #374: //Show Dots
case #375: //Show Dots Opaque
DoubleAdd(pv+1,pv+1)//num words to num bytes
ReadDots(pv+1)
endcase
default:
]
]
]

and ReadObject(n) be
[
DLEven()
[n=n-1
switchon GetWord() into
[
case 0: Show("*n Moveto ")
Shown(GetWord());Showch($*s)
Shown(GetWord());n=n-2;endcase
case 1: Show("*n Drawto ")
Shown(GetWord());Showch($*s)
Shown(GetWord());n=n-2;endcase
case 2: Show("*n DrawCurve ")
for i=1 to 6 do
[ let tempAC=vec 1
tempAC!0=GetWord()
tempAC!1=GetWord()
ShowFloat(tempAC)
Showch($*s)
n=n-2
]
endcase
]
] repeatuntil n le 0
Show("*n")
]

and ReadDots(nvec) be
[
DLEven()
let n=nil
let two=table [ 0;2]
DoubleSub(nvec,two)
switchon GetByte() into
[
case 0://full word command
switchon GetByte() into
[
case 1: n=4 //set-window
Show("*n Set Window ");endcase
case 2: n=2//set-size
Show("*n Set Size ");endcase
case 3: n=0//dots-follow
Show("*n Dots Follow*n");endcase
case 4: //Get-dots-from-file
Show("*n Get Dots From File: ")
[ let recS=GetWord();DoubleSub(nvec,two)
let len=GetByte()
let v=vec 1;v!0=0;v!1=((len/2)+1)*2;DoubleSub(nvec,v)
for i=1 to len do Showch(GetByte())
if (len&1) eq 0 then GetByte()
Show(" (record start=");Shown(recS);Show(")*n")
n=0
endcase
]
case 5: n=-1//get dots from press file
endcase
case 6:
n=GetWord()
for i=0 to n do DoubleSub(nvec,two)
Show("*n Set Sampling Properties")
while n gr 0 do switchon GetWord() into
[
case 0: Show("*n SSP input intensity: Min=")
Shown(GetWord());Show(" Max=")
Shown(GetWord())
n=n-3
endcase
case 1: Show("*n SSP output intensity: ")
for i=1 to 3 do
[ Shown(GetWord());Show(" ")]
n=n-4
endcase
case 2: Show("*n SSP screen*n")
Show(" Angle ");Shown(GetWord())
Show(" Amplitude ");Shown(GetWord())
Show(" Lines/Inch ");Shown(GetWord())
n=n-4
endcase
case 3: Show("*n SSP dot definition: (")
[ let nCells=GetWord()
Shown(nCells);Showch($,)
Shown(GetWord());Showch($,)
Shown(GetWord());Showch($))
for i=1 to nCells do GetWord()
n=n-(1+3+nCells)
endcase
]
default: Show("*n Unknown command...")
for i=2 to n do GetWord()
n=0
endcase
]
loop//back to top of routine
] //end of "switchon GetByte() into"
if n le 0 then//Dots coming now
[
let fp=vec 1
FilePos(PressFile,fp)
DoubleAdd(fp,nvec)
SetFilePos(PressFile,fp)
return
]
for i=1 to n do
[
Shown(GetWord());Showch($*s)
DoubleSub(nvec,two)
]
endcase
case 1://set coding
Show("*n Set Coding ")
Shown(GetByte());Showch($;)
Shown(GetWord());Showch($;)
Shown(GetWord())
DoubleSub(nvec,table [ 0;4])
endcase
case 2: //set mode
Show("*n Set Mode ")
Shown(GetByte())
endcase
]
] repeat