PokeByte bank,offset,value

Parameters

bank - bank handle returned by CreateBank

offset - position in the bank to write to, in bytes (0 = first byte)

value - value to store; only the low 8 bits (0-255) are kept

Description

Writes a byte into a bank.

Only the low 8 bits of the value are stored, so 0 to 255 survive exactly and anything else is wrapped (poking -1 stores 255). PeekByte reads it back.

Offsets are range checked - writing outside the bank raises a runtime error instead of trashing memory.

See also: PeekByte, PokeShort, PokeInt, PokeFloat.

Example

; PokeByte Example
; ----------------

; A player save-game record packed into a memory bank.
; Field sizes: byte=1, short=2, int=4, float=4 bytes.
;
;   offset 0   flags   (byte,  1 byte )
;   offset 1   hp      (short, 2 bytes)
;   offset 3   score   (int,   4 bytes)
;   offset 7   x_pos   (float, 4 bytes)   = 11 bytes in total

save=CreateBank(11)

; Pack the record - PokeByte writes the 1-byte flags field
; at offset 0 (values 0-255); the other Pokes fill the rest
PokeByte save,0,5
PokeShort save,1,250
PokeInt save,3,1234567
PokeFloat save,7,17.25

; Unpack the record - each Peek reads its field back
Print "Player record in a "+BankSize(save)+" byte bank:"
Print ""
Print "offset 0   flags (byte)  = "+PeekByte(save,0)
Print "offset 1   hp    (short) = "+PeekShort(save,1)
Print "offset 3   score (int)   = "+PeekInt(save,3)
Print "offset 7   x_pos (float) = "+PeekFloat(save,7)

; Dump every byte so the layout is visible
; (ints and floats are stored low byte first)
dump$=""
For i=0 To BankSize(save)-1
    dump$=dump$+PeekByte(save,i)+" "
Next
Print ""
Print "Raw bytes: "+dump$

; Release the memory when done
FreeBank save

Print ""
Print "Press any key to close the example"
WaitKey

End

Index