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Nested structures problem

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kypec

Joined: 20 Sep 2003
Posts: 54

Nested structures problem

Posted: Mon Aug 16, 2004 7:04 am

I've found a serious bug in an access to nested structures
in PCM 3.207. This error is present there since 3.190 AFAIK.
I've already sent a bug report to CCS.
See the listing file of my simple test program and you will know what I mean:

Code:

CCS PCM C Compiler, Version 3.207, 22683 16-VIII-04 14:41

Filename: D:\SOURCE\pokusy\test4.LST

ROM used: 57 words (1%)
Largest free fragment is 2048
RAM used: 29 (8%) at main() level
29 (8%) worst case
Stack: 0 locations

*
0000: MOVLW 00
0001: MOVWF 0A
0002: GOTO 004
0003: NOP
.................... #opt 0
.................... #include <16F877.h>
.................... //////// Standard Header file for the PIC16F877 device ////////////////
.................... #device PIC16F877
.................... #list
....................
.................... #device *=16 //use 16 bit pointers
....................
.................... struct outer {
.................... int8 o1;
.................... int8 o2;
.................... int16 o3;
.................... struct inner {
.................... int8 i1;
.................... int8 i2;
.................... int16 i3;
.................... } x,y;
.................... } a,b;
....................
.................... void load_inner(struct inner &ptr) {
.................... ptr.i1=1; //pointer is correct
*
000E: MOVLW 01
000F: MOVWF 24
*
0015: MOVLW 01
0016: MOVWF 28
.................... ptr.i2=2; //!!! WRONG pointer !!!
*
0010: MOVLW 02
0011: MOVWF 21
*
0017: MOVLW 02
0018: MOVWF 21
.................... ptr.i3=3; //!!! WRONG pointer !!!
*
0012: CLRF 23
0013: MOVLW 03
0014: MOVWF 22
*
0019: CLRF 23
001A: MOVLW 03
001B: MOVWF 22
.................... }
....................
.................... void load_outer(struct outer &ptr) {
.................... ptr.o1=1; //pointer is correct
001C: MOVLW 01
001D: MOVWF 20
*
002A: MOVLW 01
002B: MOVWF 2C
.................... ptr.o2=2; //pointer is correct
*
001E: MOVLW 02
001F: MOVWF 21
*
002C: MOVLW 02
002D: MOVWF 2D
.................... ptr.o3=3; //pointer is correct
*
0020: CLRF 23
0021: MOVLW 03
0022: MOVWF 22
*
002E: CLRF 2F
002F: MOVLW 03
0030: MOVWF 2E
.................... ptr.inner.i1=1; //!!! WRONG pointer !!!
*
0023: MOVLW 01
0024: MOVWF 1F
*
0031: MOVLW 01
0032: MOVWF 2B
.................... ptr.inner.i2=2; //!!! WRONG pointer !!!
*
0025: MOVLW 02
0026: MOVWF 20
*
0033: MOVLW 02
0034: MOVWF 2C
.................... ptr.inner.i3=3; //!!! WRONG pointer !!!
*
0027: CLRF 22
0028: MOVLW 03
0029: MOVWF 21
*
0035: CLRF 2E
0036: MOVLW 03
0037: MOVWF 2D
.................... }
....................
.................... void main(void) {
.................... load_inner(a.x);
*
0004: CLRF 04
0005: BCF 03.7
0006: MOVLW 1F
0007: ANDWF 03,F
0008: BSF 03.5
0009: BSF 1F.0
000A: BSF 1F.1
000B: BSF 1F.2
000C: BCF 1F.3
000D: BCF 03.5
.................... load_inner(a.y);
.................... load_outer(a);
.................... load_outer(b);
.................... }
....................
0038: SLEEP

Mark

Joined: 07 Sep 2003
Posts: 2838
Location: Atlanta, GA

Posted: Mon Aug 16, 2004 8:54 am

I am not sure if this line is valid

Code:

ptr.inner.i1=1;

If you are passing the addresses, I would use pointers instead. Like this:

Code:

#include <16F877.h>

#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=20000000)

struct outer
{
int8 o1;
int8 o2;
int16 o3;
struct inner
{
int8 i1;
int8 i2;
int16 i3;
}x,y;
} a,b;

void load_inner(struct inner *ptr)
{
ptr->i1=1;
ptr->i2=2;
ptr->i3=3;
}

void load_outer(struct outer *ptr)
{
ptr->o1=1;
ptr->o2=2;
ptr->o3=3;
ptr->x.i1=4;
ptr->x.i2=5;
ptr->x.i3=6;
}

void main(void)
{
load_inner(&a.x);
load_inner(&a.y);
load_outer(&a);
load_outer(&b);
}

You can also use the #separate which apears to work for the way you are doing it.

Code:

#include <16F877.h>

#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=20000000)

struct outer
{
int8 o1;
int8 o2;
int16 o3;
struct inner
{
int8 i1;
int8 i2;
int16 i3;
}x,y;
} a,b;

#separate
void load_inner(struct inner &ptr)
{
ptr.i1=1;
ptr.i2=2;
ptr.i3=3;
}

#separate
void load_outer(struct outer &ptr)
{
ptr.o1=1;
ptr.o2=2;
ptr.o3=3;
ptr.x.i1=4;
ptr.x.i2=5;
ptr.x.i3=6;
ptr.y.i1=7;
ptr.y.i2=8;
ptr.y.i3=9;
}

void main(void)
{
load_inner(a.x);
load_inner(a.y);
load_outer(a);
load_outer(b);
}

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