Limitation

[Peter]

Deleted...

[Charles Pegge]

Hi Peter,

Arrays are static but they can be mapped to any memory location and used as an overlay.
Ubounds do not need to be specified in this case.

To demonstrate the mapping of arrays data structures, this is my revised BMP process example. It can read the BMP header, access the pixels with an array, and create a new BMP file.

Code: OxygenBasic

1.  '===============
2. 'bmp file loader
3. '===============
4.  
5.  'Charles Pegge
6. '19:25 19/11/2011
7.  
8.  'details of BMP format:
9. 'wikipedia.org/wiki/BMP_file_format
10.  
11.  packed type BmpMapHeader
12.    short bfType
13.    long  bfSize
14.    short bfReserved1
15.    short bfReserved2
16.    long  bfOffBits
17.    long  biSize
18.    long  biWidth
19.    long  biHeight
20.    short biPlanes
21.    short biBitCount
22.    long  biCompression
23.    long  biSizeImage
24.    long  biXPelsPerMeter
25.    long  biYPelsPerMeter
26.    long  biClrUsed
27.    long  biClrImportant
28.  end type
29.  
30.  
31.   packed type pixel24
32.     byte b,g,r
33.   end type
34.  
35.  
36.   packed type pixel32
37.     byte b,g,r,a
38.   end type
39.  
40.    
41.  
42.   string bmpfile="t.bmp" 'choose your file
43.  string bmpdata
44.   getfile bmpfile,bmpdata
45.   sys le=len bmpdata
46.   '
47.  BmpMapHeader *d : @d = *bmpdata
48.  
49.   'DISPLAY HEADER VALUES
50.  '
51.  '-----------------------------------
52.  function DispBmpInfo(BmpMapHeader*d)
53.   '===================================
54.  '
55.  'capture signature to string
56.  '
57.  string n="    "
58.   **n=?d
59.   n=left n,2
60.   '
61.  string cr=chr(13)+chr(10)
62.   string tab=chr(9)
63.   string pr="BMP HEADER DATA FOR " bmpfile cr cr
64.  
65.   def    p pr=pr+ %1 tab %2 cr
66.    '
67. '------------------------------------------
68.  p  "Signature:        "  n
69.   p  "File Size:        "  d.bfSize
70.   p  "Bit data offset : "  d.bfOffBits
71.   p  "Header size:      "  d.bisize
72.   p  "Image Width:      "  d.biWidth
73.   p  "Image Height:     "  d.biHeight
74.   p  "Bit planes:       "  d.biPlanes
75.   p  "Bits per pixel:   "  d.biBitCount
76.   p  "Compression:      "  d.biCompression
77.   p  "Size of Image:    "  d.biSizeImage
78.   p  "Xpixels per metre:"  d.biXPelsPerMeter
79.   p  "Ypixels per metre:"  d.biYPelsPerMeter
80.   p  "Colours used:     "  d.biClrUsed
81.   p  "Colours important:"  d.biClrImportant
82.   '------------------------------------------
83.  
84.   print pr
85.   '
86.  end function
87.  
88.  
89.   if bmpdata then DispBmpInfo d
90.  
91.  
92.   'TEST PIXEL READING
93.  '==================
94.  
95.   'pixel24 *pix : @pix = *BmpData + d.bfOffBits
96.  'print pix(1).r
97.  
98.  
99.   'CREATE A BMP FILE FROM SCRATCH
100.  '==============================
101.  
102.   pixel24 *pix '3 color pixel
103.  sys offs=64, w=16, h=16, bits=8*sizeof pix
104.   BmpMapHeader *hdr
105.   sys le=offs+w*h*sizeof pix
106.   BmpData=nuls le
107.   @hdr = *BmpData   'map header overlay
108.  @pix = @hdr+offs  'map pixel overlay
109.  
110.  
111.   'ENTER METRICS INTO THE HEADER
112.  '=============================
113.  
114.   hdr<=0x4d42,le,0,0,offs,40,w,h,1,bits,0,w*h*sizeof pix
115.  
116.  
117.   'FILL IN PIXELS
118.  '==============
119.  
120.   scope
121.  
122.   indexbase 0
123.   for y=1 to 14
124.      for x=1 to 14
125.        pix(y*w+x)<=0,160,128 ' b g r
126.    next
127.   next
128.  
129.   end scope  
130.  
131.  
132.   'SAVE BMP FILE
133.  '=============
134.  
135.   string fname="s.bmp"
136.   putfile fname,BmpData
137.   print "Created: " fname
138.  
139.  
140.   '====
141.  done:
142.   '====
143.  
144.   BmpData=""
145.  
146.  
147. '=====
148. 'NOTES
149. '=====
150.  
151. '----------------------------------------------------------------------------------------------------------
152. ' BMP file formats
153. '
154. ' The BITMAPFILEHEADER:
155. '----------------------------------------------------------------------------------------------------------
156. 'start size name           description
157. '----------------------------------------------------------------------------------------------------------
158. '0     2    bfType         must always be set to 'BM' to declare that this is a .bmp-file.
159. '2     4    bfSize         the size of the file in bytes.
160. '4     2    bfReserved1    must always be set to zero.
161. '8     2    bfReserved2    must always be set to zero.
162. '10    4    bfOffBits      the offset from the beginning of the file to the bitmap data.
163. '----------------------------------------------------------------------------------------------------------
164. '
165. '
166. ' The BITMAPINFOHEADER:
167. '----------------------------------------------------------------------------------------------------------
168. 'start size name            description
169. '----------------------------------------------------------------------------------------------------------
170. '14    4    biSize          size of the BITMAPINFOHEADER structure, in bytes.
171. '18    4    biWidth         width of the image, in pixels.
172. '22    4    biHeight        height of the image, in pixels.
173. '26    2    biPlanes        number of planes of the target device, must be set to zero.
174. '28    2    biBitCount      number of bits per pixel.
175. '30    4    biCompression   type of compression, usually set to zero (no compression).
176. '34    4    biSizeImage     size of the image data, in bytes. If there is no compression, it is valid to set this member to zero.
177. '38    4    biXPelsPerMeter horizontal pixels per meter on the designated targer device, usually set to zero.
178. '42    4    biYPelsPerMeter vertical pixels per meter on the designated targer device, usually set to zero.
179. '46    4    biClrUsed       number of colors used in the bitmap, if set to zero the number of colors is calculated using the biBitCount member.
180. '50    4    biClrImportant  number of color that are 'important' for the bitmap, if set to zero, all colors are important.
181. '----------------------------------------------------------------------------------------------------------
182.  
183.  

Charles

[efgee]

What means this: codeout = code1 ? code1 : code2

Suppose it means if code1 is true than codeout equals code1 otherwise codeout equals code2

[Charles Pegge]

I don't know what it means.  In Oxygen  '?' is a cast operator equivalent to <sys>

bstring s="ok"
print ? s
print <sys> s


Peter,

You can do multiple assignments like this. I have just checked

sys a,b,c,d
if a=0 then a=b=c=d=42
print a "   " b "    " c  "    " d


But the variables have to be declared first. Autodim only works for one variable at a time.

Charles

[Charles Pegge]

Peter,

Here is one way to create dynamic arrays. These can be dimensioned by a variable at run time but should be erased when finished.

def dynamic %1 * %2 : @ %2=getmemory %3 * sizeof %2

Code: OxygenBasic

1. 'dynamic dim
2. '===========
3.  
4. def dynamic %1 * %2 : @ %2=getmemory %3 * sizeof %2
5.  
6. sys a=10*5
7.  
8. dynamic string d a
9.  
10.  
11. d[a-7]=999
12. print d[a-7]
13. freememory @d
14.  

Charles

[Charles Pegge]

They will not self-destruct in 10 seconds