Maximum array size?

[thomas]

Hello,

I am using PIC16F876 with CCS version 3.0. When I write "int array[256];" It flags an error, saying that the maximum subscription is exceeded. What is the maxium size for an array? How do allocate 256 byte? This PIC has more than 256 bytes of RAM. Is it not?
Thanks!
Thomas
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This message was ported from CCS's old forum
Original Post ID: 144515263

[Haplo]

Thomas,
I'm quoting this from the CCS help:
"A subscript to a RAM array must be at least 1 and not more than 128 elements. Note that large arrays might not fit in a bank. ROM arrays may not occupy more than 256 locations. Arrays are limited to 5 dimensions."

Note that although PIC16F87 has 368 bytes of memory, it's divided in 4 banks. Compiler can't allocate an array over more than one bank, so your array sizes are limited to the bank size.

Ali
___________________________
This message was ported from CCS's old forum
Original Post ID: 144515267

[Mike Broom]

:=Hello,
:=
:=I am using PIC16F876 with CCS version 3.0. When I write "int array[256];" It flags an error, saying that the maximum subscription is exceeded. What is the maxium size for an array? How do allocate 256 byte? This PIC has more than 256 bytes of RAM. Is it not?
:=Thanks!
:=Thomas

Thomas the following code snippit will do what you want, and can actually address all available ram with a little tweaking of the #reserve's and an additional a bit of code to address bank 0 RAM

regards

Mike Broom

[thomas]

Perfect! This is jus what I need. Thank you very much!
thomas
:=:=Hello,
:=:=
:=:=I am using PIC16F876 with CCS version 3.0. When I write "int array[256];" It flags an error, saying that the maximum subscription is exceeded. What is the maxium size for an array? How do allocate 256 byte? This PIC has more than 256 bytes of RAM. Is it not?
:=:=Thanks!
:=:=Thomas
:=
:=Thomas the following code snippit will do what you want, and can actually address all available ram with a little twaking of the #reserve's and an additional a bit of code to address bank 0 RAM
:=
:=regards
:=
:=Mike Broom
:=
:=#include <16f876.h>
:=
:=#reserve 0xa0:0xef
:=#reserve 0x110:0x16f
:=#reserve 0x190:0x1df
:=
:=void WriteArray(int16 Index, int8 Value)
:={
:= int8 Bank;
:= int8 Offset;
:=
:= Bank = 1; //Start in bank 1 no offset
:= Offset = Index;
:= if(Index >= 0x50)
:= {
:= Bank = 2; //Jump to bank 2 when we have filled bank 1
:= Offset = (Index - 0x50); //subtract size of bank 1
:= }
:= if(Index >= 0xB0)
:= {
:= Bank = 3; //Jump to bank 3 and subtract
:= Offset = (Index - 0xB0); //Size bank 1 & 2
:= }
:= switch(Bank)
:= {
:= case 1:
:= write_bank(1,Offset,Value);
:= break;
:= case 2:
:= write_bank(2,Offset,Value);
:= break;
:= case 3:
:= write_bank(3,Offset,Value);
:= break;
:= default:
:= break;
:= }
:=}
:=
:=int8 ReadArray(int16 Index)
:={
:= int8 Bank;
:= int8 Offset;
:=
:= Bank = 1; //Start in bank 1 no offset
:= if(Index >= 0x50)
:= {
:= Bank = 2; //Jump to bank 2 when we have filled bank 1
:= Offset = (Index - 0x50); //subtract size of bank 1
:= }
:= if(Index >= 0xB0)
:= {
:= Bank = 3; //Jump to bank 3 and subtract
:= Offset = (Index - 0x60); //Size bank 1 & 2
:= }
:= switch(Bank)
:= {
:= case 1:
:= return(read_bank(1,Offset));
:= break;
:= case 2:
:= return(read_bank(1,Offset));
:= break;
:= case 3:
:= return(read_bank(1,Offset));
:= break;
:= default:
:= break;
:= }
:=}
:=
:=void main(void)
:={
:= WriteArray(MyArray_Element,Value); //This will write to any cell upto 256
:= MyArray_Element_Value = ReadArray(MyArray_Element); //This will read fro the array
:=}
___________________________
This message was ported from CCS's old forum
Original Post ID: 144515303