Efficient copying of structures

[PaulAntonucci]

Hello:

I have the following problem: I need to very quickly copy a structure. I have an older version of my program which uses an 8 byte structure and a "copy" compiles nicely and efficiently as follows:


struct object_descriptor {
byte y_start;
byte y_end;
long x_up_total;
long x_down_total;
byte previous_x_up;
byte previous_x_down;
};

struct object_descriptor C1_object1, C1_object2, C2_object1, C2_object2;



.................... C2_object2 = C2_object1;
05D0: MOVF 36,W
05D1: MOVWF 3E
05D2: MOVF 37,W
05D3: MOVWF 3F
05D4: MOVF 38,W
05D5: MOVWF 40
05D6: MOVF 39,W
05D7: MOVWF 41
05D8: MOVF 3A,W
05D9: MOVWF 42
05DA: MOVF 3B,W
05DB: MOVWF 43
05DC: MOVF 3C,W
05DD: MOVWF 44
05DE: MOVF 3D,W
05DF: MOVWF 45


However, I recently expanded the data structure to 9 bytes (by adding bit fields) and the copy sets up pointers and is very time consuming as follows:

struct object_descriptor {
byte y_start;
byte y_end;
long x_up_total;
long x_down_total;
byte previous_x_up;
byte previous_x_down;
short field_index, y_start_overflow, y_end_overflow, object_started;
};


.................... C1_object2 = C1_object1;
0B32: MOVLW 2F
0B33: MOVWF 64
0B34: MOVLW 26
0B35: MOVWF 63
0B36: MOVLW 09
0B37: MOVWF 78
0B38: MOVF 63,W
0B39: MOVWF 04
0B3A: MOVF 00,W
0B3B: MOVWF 77
0B3C: MOVF 64,W
0B3D: MOVWF 04
0B3E: MOVF 77,W
0B3F: MOVWF 00
0B40: INCF 63,F
0B41: INCF 64,F
0B42: DECFSZ 78,F
0B43: GOTO 338

Do you have a solution for this problem ?

Thanks !!

Paul Antonucci
_________________
Paul Antonucci
[email protected]

[PCM programmer]

You may have to manually copy each element of the structure.
In terms of C code, it's messy, but it does produce the efficient
assembly code that you desire. Example:

C1_object2.y_start = C1_object1.y_start;
.
.
.
C1_object2.field_index = C1_object1.field_index;

etc.

[KerryW]

Try

MEMCPY(C1_object2, C1_object1, SIZEOF(C1_object1);

[PCM programmer]

I looked at memcpy before I posted my answer.
The problem with memcpy is that it produces the same
code (with pointers) that he doesn't like.