Union

Forum for discussion about the documentation project.
Tourist Trap
Posts: 2751
Joined: Jun 02, 2015 16:24

Re: Union

Postby Tourist Trap » Dec 13, 2018 14:12

fxm wrote:Last attempt for me (this strange and twisted use of Union is not very exciting):

Anyway it seems that you made it work.

I don't know from my part if it is strange or twisted , I just can't see a really useful other usage of Unions beyond the color example (I'm obviously a great ignorant in this but it's how it is at the day of today). By the way we learnt a lot on number representation in memory, on zstrings and strings with some details that are exhibited here crudely that may be very hard to see otherwise (like null bytes issues, in the middle of the string as well as for terminators in zstrings).

About the converting excercise, even if it's surprisingly hard to twist as you say, I think that the hardest part is done with the converting to the base-256. Now that you've helped a lot with this case, I'll try when I'll have some time to add the other 8n bases. This is a recurrent issue to convert a number into another representation around here. I think that this case was a little extreme, but the base 128 could be quite useful to solve (easier?).

Thanks again.
Tourist Trap
Posts: 2751
Joined: Jun 02, 2015 16:24

Re: Union

Postby Tourist Trap » Dec 13, 2018 17:54

Little demo, about exhibiting the byte array behaviour.
Thanks to dodicat for the fonts from its Pool game (game section around here).

Code: Select all

'illustration of the UNION internal mechanics

union InsideAnOnion
    declare constructor()
    declare constructor(byval Value as uinteger<8*8>)
    declare constructor(UbyteArray() as ubyte)
    declare sub DrawOnion(byval Fount as any ptr)
        as uinteger<8*8>    _value
        as ubyte            _ubyteArray(7)
end union
type IAO as InsideAnOnion
constructor IAO()
    THIS._value => 0
end constructor
constructor IAO(byval Value as uinteger<8*8>)
    THIS._value => Value
end constructor
constructor IAO(UbyteArray() as ubyte)
    if ((ubound(UbyteArray) - lbound(UbyteArray) + 1)>=8) then
        for zeroBasedIndex as integer = 0 to 7
            THIS._ubyteArray(zeroBasedIndex) = UbyteArray(lbound(UbyteArray) + zeroBasedIndex)
        next zeroBasedIndex
    else
        for zeroBasedIndex as integer = 0 to ubound(UbyteArray) - lbound(UbyteArray)
            THIS._ubyteArray(zeroBasedIndex) = UbyteArray(lbound(UbyteArray) + zeroBasedIndex)
        next zeroBasedIndex
    end if
end constructor
sub IAO.DrawOnion(byval Fount as any ptr)
    dim as integer  scrW, scrH
    screenInfo      scrW, scrH
    '
    dim as integer  gfxArrayW   => 8*34
    dim as integer  gfxArrayH   => 34
    line    ((scrW - gfxArrayW)\2 - 1, (scrH - gfxArrayH)\2 - scrH/10 - 1)- _
        step(gfxArrayW + 2, gfxArrayH + 2), rgb(180,180,220), B
    line    ((scrW - gfxArrayW)\2 - 2, (scrH - gfxArrayH)\2 - scrH/10 - 2)- _
        step(gfxArrayW + 4, gfxArrayH + 4), rgb(180,240,180), B
    line ((scrW - gfxArrayW)\2, (scrH - gfxArrayH)\2 - scrH/10)-step(gfxArrayW, 0)
    line ((scrW - gfxArrayW)\2, (scrH - gfxArrayH)\2 - scrH/10 + gfxArrayH)-step(gfxArrayW, 0)
    for i as integer = 0 to 7 + 1
        line ((scrW - gfxArrayW)\2 + gfxArrayW*i\8, (scrH - gfxArrayH)\2 - scrH/10)-step(0, gfxArrayH)
    next i
    '
    'draw the integer value
    dim as integer  valueStringLength   => len(str(THIS._value))
    draw string ((scrW - valueStringLength*16)\2,(scrH - gfxArrayH*4)\2 - scrH/10 ), _
                                                            str(THIS._value),,Fount
    '
    'draw the array of bytes
    for i as integer = 0 to 7
        if THIS._ubyteArray(7 - i)<16 then
            draw string ((scrW - gfxArrayW)\2 + gfxArrayW*i\8 + 16,(scrH - gfxArrayH)\2 - scrH/10 ), _
                                                                    hex(THIS._ubyteArray(7 - i)),,Fount
            draw string ((scrW - gfxArrayW)\2 + gfxArrayW*i\8,(scrH - gfxArrayH)\2 - scrH/10 ), _
                                                                    "0",,Fount
        else
            draw string ((scrW - gfxArrayW)\2 + gfxArrayW*i\8,(scrH - gfxArrayH)\2 - scrH/10 ), _
                                                                    hex(THIS._ubyteArray(7 - i)),,Fount
        end if
    next i
end sub

'with a big thank to dodicat for his fonts...
namespace dodifont
    declare Function Filter(Byref tim As Ulong Pointer,Byval rad As Single,Byval destroy As Long=1,Byval fade As Long=0) As Ulong Pointer
    declare Sub drawstring(Byval xpos As Long,Byval ypos As Long,Byref text As String,Byval co As Ulong,Byval size As Single,Byref im As Any Pointer=0)
    declare Function Colour(Byref im As Any Pointer,Byval newcol As Ulong,Byval tweak As Long,Byval fontsize As Single) As Any Pointer
    declare Sub CreateFont(Byref myfont As Any Pointer,Byval fontsize As Single,Byval col As Ulong,Byval tweak As Long=0)
    Sub init Constructor
        drawstring(0,0,"",0,0)
        Screen 0
    End Sub
end namespace
using dodifont

'---------------------------------------------------------------------------MAIN
#include "fbgfx.bi"
randomize TIMER
screenres 840,400,32, _
         2, _                               'sets application screen page number
            fb.GFX_SHAPED_WINDOW   + _               'enables application standard transparency
            fb.GFX_ALPHA_PRIMITIVES   + _               'enables application standard alpha
            fb.GFX_NO_FRAME
color , rgb(110,110,125)
cls

dim as IAO  iaoInstance
Dim As Any Ptr starter
createfont starter,2,Rgb(200,200,200),10
   
Do
    screenset   0, 1
        Cls
        line(2,2)-(837,597),rgb(200,200,235),b
        ?
        ? "demo"
        ? "press <ANY KEY> to pause/restart"
        ? "press <ESC> many times to exit
        iaoInstance = IAO(rnd()*10^(rnd()*18))
        iaoInstance.DrawOnion(starter)
    screencopy  0, 1
    Sleep 1000,1
    if Len(Inkey) then getKey()
Loop Until inkey()=chr(27)

getKey()
'---------------------------------------------------------------------------END
dodicatfontmanagement:
        Function Filter(Byref tim As Ulong Pointer,_
        Byval rad As Single,_
        Byval destroy As Long=1,_
        Byval fade As Long=0) As Ulong Pointer
        #define map(a,b,_x_,c,d) ((d)-(c))*((_x_)-(a))/((b)-(a))+(c)
        If fade<0 Then fade=0:If fade>100 Then fade=100
        Type p2 : As Long x,y : As Ulong col : End Type
        #macro ppoint(_x,_y,colour): pixel=row+pitch*(_y)+(_x)*4 : (colour)=*pixel
        #endmacro
        #macro ppset(_x,_y,colour)
        pixel=row+pitch*(_y)+(_x)*4 : *pixel=(colour)
        #endmacro
        #macro average()
        ar=0:ag=0:ab=0:inc=0 : xmin=x:If xmin>rad Then xmin=rad
        xmax=rad:If x>=(_x-1-rad) Then xmax=_x-1-x
        ymin=y:If ymin>rad Then ymin=rad
        ymax=rad:If y>=(_y-1-rad) Then ymax=_y-1-y
        For y1 As Long=-ymin To ymax : For x1 As Long=-xmin To xmax
        inc=inc+1 : ar=ar+(NewPoints(x+x1,y+y1).col Shr 16 And 255)
        ag=ag+(NewPoints(x+x1,y+y1).col Shr 8 And 255)
        ab=ab+(NewPoints(x+x1,y+y1).col And 255) : Next x1
        Next y1 : If fade=0 Then
        averagecolour=Rgb(ar/(inc),ag/(inc),ab/(inc))
        Else
        averagecolour=Rgb(fd*ar/(inc),fd*ag/(inc),fd*ab/(inc))
        End If
        #endmacro
        Dim As Single fd=map(0,100,fade,1,0) : Dim As Integer _x,_y : Imageinfo tim,_x,_y
        Dim  As Ulong Pointer im=Imagecreate(_x,_y) : Dim As Integer pitch : Dim  As Any Pointer row
        Dim As Ulong Pointer pixel : Dim As Ulong col : Imageinfo tim,,,,pitch,row : Dim As p2 NewPoints(_x-1,_y-1)
        For y As Long=0 To (_y)-1 : For x As Long=0 To (_x)-1 : ppoint(x,y,col)
        NewPoints(x,y)=Type<p2>(x,y,col) : Next x : Next y : Dim As Ulong averagecolour
        Dim As Long ar,ag,ab : Dim As Long xmin,xmax,ymin,ymax,inc : Imageinfo im,,,,pitch,row
        For y As Long=0 To _y-1 : For x As Long=0 To _x-1 : average() : ppset((NewPoints(x,y).x),(NewPoints(x,y).y),averagecolour)
        Next x : Next y : If destroy Then Imagedestroy tim: tim = 0
        Function= im : End Function
        Sub drawstring(Byval xpos As Long,Byval ypos As Long,Byref text As String,Byval co As Ulong,Byval size As Single,Byref im As Any Pointer=0)
        Type D2
        As Double x,y
        As Ulong col
        End Type
        size=Abs(size) : Static As d2 XY() : Static As Long runflag
        If runflag=0 Then   
        Redim  XY(128,127): Screen 8 : Width 640\8,200\16 : Dim As Ulong Pointer img
        Dim count As Long : For ch As Long=1 To 127 : img=Imagecreate(9,17) : Draw String img,(1,1),Chr(ch)
        For x As Long=1 To 8 : For y As Long=1 To 16 : If Point(x,y,img)<>0 Then
            count=count+1
            XY(count,ch)=Type<D2>(x,y)
        End If : Next y : Next x : count=0 : Imagedestroy img : Next ch
        runflag=1 : End If
        If size=0 Then Exit Sub
        Dim As D2 np,t
        #macro Scale(p1,p2,d)
        np.col=p2.col
        np.x=d*(p2.x-p1.x)+p1.x
        np.y=d*(p2.y-p1.y)+p1.y
        #endmacro
        Dim As D2 c=Type<D2>(xpos,ypos) : Dim As Long dx=xpos,dy=ypos,f
        If Abs(size)=1.5 Then f=3 Else f=2
        For z6 As Long=1 To Len(text)
        Var asci=text[z6-1] : For _x1 As Long=1 To 64*2
        t=Type<D2>(XY(_x1,asci).x+dx,XY(_x1,asci).y+dy,co)         
        Scale(c,t,size)
        If XY(_x1,asci).x<>0 Then
        If size>1 Then
        Line im,(np.x-size/f,np.y-size/f)-(np.x+size/f,np.y+size/f),np.col,bf
        Else
        Pset im,(np.x,np.y),np.col
        End If : End If : Next _x1
        dx=dx+8 : Next z6: End Sub 
        Function Colour(Byref im As Any Pointer,Byval newcol As Ulong,Byval tweak As Long,Byval fontsize As Single) As Any Pointer
        #macro ppset2(_x,_y,colour)
        pixel2=row2+pitch2*(_y)+(_x)*dpp2
        *pixel2=(colour)
        #endmacro
        #macro ppoint(_x,_y,colour)
        pixel=row+pitch*(_y)+(_x)*dpp
        (colour)=*pixel
        #endmacro
        Dim As Long grade : Select Case  fontsize
        Case 1 To 1.5:grade=205
        Case 2 :grade=225
        Case 2.5:grade=222
        Case 3 To 3.5:grade=200
        Case 4 To 4.5:grade=190
        Case 5 To 5.5:grade=165
        Case Else: grade=160
        End Select
        Dim As Integer w,h : Dim As Integer pitch,pitch2,dpp,dpp2 : Dim  As Any Pointer row,row2 : Dim As Ulong Pointer pixel,pixel2
        Dim As Ulong col : Imageinfo im,w,h,dpp,pitch,row : Dim As Any Pointer temp=Imagecreate(w,h)
        Imageinfo temp,,,dpp2,pitch2,row2 : For y As Long=0 To h-1
        For x As Long=0 To w-1 : ppoint(x,y,col) : Var v=.299*((col Shr 16)And 255)+.587*((col Shr 8)And 255)+.114*(col And 255)
        If v>(grade+tweak) Then
        ppset2(x,y,newcol)
        Else
        ppset2(x,y,Rgb(255,0,255))
        End If : Next x : Next y : Return temp : End Function
        Sub CreateFont(Byref myfont As Any Pointer,Byval fontsize As Single,Byval col As Ulong,Byval tweak As Long=0)
        fontsize=Int(2*Abs(fontsize))/2 : If fontsize=0 Then fontsize=.5
        Dim As Ubyte Ptr p : Dim As Any Pointer temp
        Dim As Integer i : temp = Imagecreate(FontSize*768,FontSize*16) : myfont=Imagecreate(FontSize*768,FontSize*16)
        For i = 32 To 127 : drawstring ((i-32)*FontSize*8,1,Chr(i),Rgb(255,255,255),FontSize,temp)
        Next i : If fontsize>1.5 Then
        For n As Single=0 To fontsize-2:temp=filter(temp,1,1,0):Next
        End If : temp=Colour(temp,col,tweak,fontsize) : Put myfont,(0,0),temp,trans : Imageinfo( myfont,i,,,, p )
        p[0]=0:p[1]=32:p[2]=127 : For i = 32 To 127 : p[3+i-32]=FontSize*8 : Next i : Imagedestroy(temp) : End Sub
'(eof)
Tourist Trap
Posts: 2751
Joined: Jun 02, 2015 16:24

Re: Union

Postby Tourist Trap » Dec 13, 2018 19:56

This also is giving interesting details on how things are stored:

Code: Select all

union InsideAnOnion
        type
            as uinteger<8*8>    _value
            as uinteger<8*4>    _value2
        end type
        as ubyte            _ubyteArray(7)   ''of no use in this demo
end union
type IAO as InsideAnOnion

dim as IAO  iaoInstance

iaoInstance._value  = &hAABBCCDDEEFF1122
iaoInstance._value2 = &h33445566EE8899CC
for i as integer = 0 to 7 + 8
    ? hex(*cptr(ubyte ptr, cptr(ubyte ptr, @iaoInstance) +  i*1));
next i:?

'output
'2211FFEEDDCCBBAACC9988EE0000


for some reason *cptr(ubyte ptr, @iaoInstance) = *cptr(ubyte ptr, cptr(ubyte ptr, @iaoInstance))? But :

Code: Select all

for i as integer = 0 to 7 + 8
    ? hex(*cptr(ubyte ptr, cptr(ubyte ptr, @iaoInstance) +  i*1));
next i:?
'BA11FFEEDDCCBBAACC9988EE0000

for i as integer = 0 to 7 + 8
    ? hex(*cptr(ubyte ptr, @iaoInstance + i*1)); 
next i:?
'BA406320B0389000705F00EA0

Weird? Obviously I'm missing the trick...
coderJeff
Site Admin
Posts: 2841
Joined: Nov 04, 2005 14:23
Location: Ontario, Canada
Contact:

Re: Union

Postby coderJeff » Dec 15, 2018 16:19

Pay careful attention to the pointer math:
@variable + offset
is like saying
cptr( typeof(variable) ptr, cptr( ubyte ptr, @variable ) + offset * sizeof( typeof(variable) ) )

Adding or subtracting a scalar (number) to a typed pointer is in multiples of the pointed to type size.

EDIT: missed a few things in the translations... added now.

Return to “Documentation”

Who is online

Users browsing this forum: fxm and 1 guest