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vtrx
Joined: 11 Oct 2017
Posts: 141
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| How to load a content of a variable to port in ASM ? |
 Posted: Thu Oct 04, 2018 6:35 am |
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I'm trying to optimize a code to give exit in PORTB:
| Code: | void Saida()
{
int8 count;
#asm
movlw 121
movwf count
SAIDA:
// movlw 5//Buf_VGA[count] ERROR
movwf PORTB
decfsz count
goto SAIDA
FIM:
#endasm
} |
GLOBAL
int8 Buf_VGA[244]={...
How can I do it? |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19215
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| Posted: Thu Oct 04, 2018 7:46 am |
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You need to tell us the chip.
You are going to have to use indirect addressing, where you have a 'pointer' that says 'where' the value is going to come 'from', and increment this for each byte. Indirect addressing uses very different instructions on different PIC's...
Funnily enough, there is a thread just running about CRC's which shows a fairly generic fetch for most PIC's. So using this:
| Code: |
// Setup Index Register locations (FSR and INDF)
#if defined(__PCM__) // For example (and tested on) PIC16F74, PIC16F887
#byte FSR = GETENV("SFR:FSR")
#byte INDF = GETENV("SFR:INDF")
#elif defined(__PCH__) // For example (and tested on) PIC18F458
#word FSR = GETENV("SFR:FSR0L")
#byte POSTINC0 = GETENV("SFR:POSTINC0")
#else
#Error You need to setup the above for your PIC chip
#endif
void Saida(byte * data)
{
int8 count=121; //Why? you say the array is 244 bytes?
#asm
Loop: //must not be the same name as the function
#if defined(__PCM__)
movf INDF, W // load W with next databyte
incf FSR // do a 8-bit increment - increment indirection register to point to next databyte - for the next time
#elif defined(__PCH__)
movf POSTINC0, W // load w with next databyte and increment indirection register to point to next databyte - for the next time
#else
#Error You need to setup the above for your PIC Chip
#endif
movwf PORTB
decfsz count, F
goto loop // loop for next byte
#endasm
}
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Except for the oddity of having a 244 byte array, and a count of only 121, this should output the bytes basically as fast as possible. |
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vtrx
Joined: 11 Oct 2017
Posts: 141
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| Posted: Thu Oct 04, 2018 8:53 am |
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Thank you for helping me.
The PIC is 18F2550.
I am trying to program a VGA output but for the CCS compiler.
Using :
| Code: | | for(x=0; x<120 ; x++){ output_b(out_vga[x]);} |
is very slow and desynchronizes the routine that is in the timer.
I'm using this for one line:
| Code: | void saida_vga(void)
{
output_b(out_vga[0]);
output_b(out_vga[1]);
output_b(out_vga[2]);
output_b(out_vga[3]);
output_b(out_vga[4]);
output_b(out_vga[5]);
output_b(out_vga[6]);
output_b(out_vga[7]);
output_b(out_vga[8]);
output_b(out_vga[9]);
output_b(out_vga[10]);
output_b(out_vga[11]);
output_b(out_vga[12]);
output_b(out_vga[13]);
output_b(out_vga[14]);
output_b(out_vga[15]);
output_b(out_vga[16]);
output_b(out_vga[17]);
output_b(out_vga[18]);
output_b(out_vga[19]);
output_b(out_vga[20]);
output_b(out_vga[21]);
output_b(out_vga[22]);
output_b(out_vga[23]);
output_b(out_vga[24]);
output_b(out_vga[25]);
output_b(out_vga[26]);
output_b(out_vga[27]);
output_b(out_vga[28]);
output_b(out_vga[29]);
output_b(out_vga[30]);
output_b(out_vga[31]);
output_b(out_vga[32]);
output_b(out_vga[33]);
output_b(out_vga[34]);
output_b(out_vga[35]);
output_b(out_vga[36]);
output_b(out_vga[37]);
output_b(out_vga[38]);
output_b(out_vga[39]);
output_b(out_vga[40]);
output_b(out_vga[41]);
output_b(out_vga[42]);
output_b(out_vga[43]);
output_b(out_vga[44]);
output_b(out_vga[45]);
output_b(out_vga[46]);
output_b(out_vga[47]);
output_b(out_vga[48]);
output_b(out_vga[49]);
output_b(out_vga[50]);
output_b(out_vga[51]);
output_b(out_vga[52]);
output_b(out_vga[53]);
output_b(out_vga[54]);
output_b(out_vga[55]);
output_b(out_vga[56]);
output_b(out_vga[57]);
output_b(out_vga[58]);
output_b(out_vga[59]);
output_b(out_vga[60]);
output_b(out_vga[61]);
output_b(out_vga[62]);
output_b(out_vga[63]);
output_b(out_vga[64]);
output_b(out_vga[65]);
output_b(out_vga[66]);
output_b(out_vga[67]);
output_b(out_vga[68]);
output_b(out_vga[69]);
output_b(out_vga[70]);
output_b(out_vga[71]);
output_b(out_vga[72]);
output_b(out_vga[73]);
output_b(out_vga[74]);
output_b(out_vga[75]);
output_b(out_vga[76]);
output_b(out_vga[77]);
output_b(out_vga[78]);
output_b(out_vga[79]);
output_b(out_vga[80]);
output_b(out_vga[81]);
output_b(out_vga[82]);
output_b(out_vga[83]);
output_b(out_vga[84]);
output_b(out_vga[85]);
output_b(out_vga[86]);
output_b(out_vga[87]);
output_b(out_vga[88]);
output_b(out_vga[89]);
output_b(out_vga[90]);
output_b(out_vga[91]);
output_b(out_vga[92]);
output_b(out_vga[93]);
output_b(out_vga[94]);
output_b(out_vga[95]);
output_b(out_vga[96]);
output_b(out_vga[97]);
output_b(out_vga[98]);
output_b(out_vga[99]);
output_b(out_vga[100]);
output_b(out_vga[101]);
output_b(out_vga[102]);
output_b(out_vga[103]);
output_b(out_vga[104]);
output_b(out_vga[105]);
output_b(out_vga[106]);
output_b(out_vga[107]);
output_b(out_vga[108]);
output_b(out_vga[109]);
output_b(out_vga[110]);
output_b(out_vga[111]);
output_b(out_vga[112]);
output_b(out_vga[113]);
output_b(out_vga[114]);
output_b(out_vga[115]);
output_b(out_vga[116]);
output_b(out_vga[117]);
output_b(out_vga[118]);
output_b(out_vga[119]);
output_b(out_vga[120]);
output_b(out_vga[121]);
output_b(0);
} |
I need to change the index for each line. |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19215
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| Posted: Thu Oct 04, 2018 10:13 am |
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That is what the code I've posted does. On the PIC18, there is a special instcuction which post increments a RAM pointer when you use it. What is missing, is the address setup:
| Code: |
void Saida(byte * data)
{
int8 count=121; //Why? you say the array is 244 bytes?
#asm
#if defined(__PCM__)
movf data, W // copy pointer to w reg..
movwf FSR // ..to pointer register
#elif defined(__PCH__)
movff data, FSR0L // copy low byte of pointer to low byte of pointer register 0..
movff &p_data+1, FSR0H // copy high byte of pointer to high byte of pointer register 0..
#else
#Error You need to setup the above for your PIC Chip
#endif
Loop: //must not be the same name as the function
#if defined(__PCM__)
movf INDF, W // load W with next databyte
incf FSR // do a 8-bit increment - increment indirection register to point to next databyte - for the next time
#elif defined(__PCH__)
movf POSTINC0, W // load w with next databyte and increment indirection register to point to next databyte - for the next time
#else
#Error You need to setup the above for your PIC Chip
#endif
movwf PORTB
decfsz count, F
goto loop // loop for next byte
#endasm
}
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This needs to be called with the address of the data, so:
Saida(Buf_VGA);
It should code as 4 instruction times per byte (a loop takes two instruction times). |
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vtrx
Joined: 11 Oct 2017
Posts: 141
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| Posted: Thu Oct 04, 2018 10:28 am |
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Compiler show a error:
*** Error 28 "main.c" Line 412(10,15): Expecting an identifier
on:
movff data, FSR0L |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19215
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| Posted: Thu Oct 04, 2018 10:51 am |
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You need the setup stuff loaded before it is used. The:
| Code: |
// Setup Index Register locations (FSR and INDF)
#if defined(__PCM__) // For example (and tested on) PIC16F74, PIC16F887
#byte FSR = GETENV("SFR:FSR")
#byte INDF = GETENV("SFR:INDF")
#elif defined(__PCH__) // For example (and tested on) PIC18F458
#word FSR = GETENV("SFR:FSR0L")
#byte POSTINC0 = GETENV("SFR:POSTINC0")
#else
#Error You need to setup the above for your PIC chip
#endif
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temtronic
Joined: 01 Jul 2010
Posts: 9097
Location: Greensville,Ontario
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| Posted: Thu Oct 04, 2018 10:54 am |
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hmm.... FSROL should be FSR0L
Is that a captial 'O' ?
It should be the number '0' ( zero).
very hard to tell with the font, but if you look at Mr. T.'s post you can just see a slight differenec in an 'O' versus a '0'.
in this msg the 0 (zero) is thinner.
Jay |
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vtrx
Joined: 11 Oct 2017
Posts: 141
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| Posted: Thu Oct 04, 2018 10:59 am |
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This way?
| Code: | // Setup Index Register locations (FSR and INDF)
#if defined(__PCM__) // For example (and tested on) PIC16F74, PIC16F887
#byte FSR = GETENV("SFR:FSR")
#byte INDF = GETENV("SFR:INDF")
#elif defined(__PCH__) // For example (and tested on) PIC18F458
#word FSR = GETENV("SFR:FSR0L")
#byte POSTINC0 = GETENV("SFR:POSTINC0")
#else
#Error You need to setup the above for your PIC chip
#endif
void Saida(byte * data)
{
int8 count=121; //Why? you say the array is 244 bytes?
#asm
Loop: //must not be the same name as the function
#if defined(__PCM__)
movf INDF, W // load W with next databyte
incf FSR // do a 8-bit increment - increment indirection register to point to next databyte - for the next time
#elif defined(__PCH__)
movf POSTINC0, W // load w with next databyte and increment indirection register to point to next databyte - for the next time
#else
#Error You need to setup the above for your PIC Chip
#endif
movwf PORTB
decfsz count, F
goto loop // loop for next byte
#endasm
} |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19215
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| Posted: Thu Oct 04, 2018 11:01 am |
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| No that is missing the stuff that actually programs the FSR. That's why I posted the modified version of the function. |
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vtrx
Joined: 11 Oct 2017
Posts: 141
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| Posted: Thu Oct 04, 2018 11:03 am |
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Can't compile this code:
| Code: | // Setup Index Register locations (FSR and INDF)
#if defined(__PCM__) // For example (and tested on) PIC16F74, PIC16F887
#byte FSR = GETENV("SFR:FSR")
#byte INDF = GETENV("SFR:INDF")
#elif defined(__PCH__) // For example (and tested on) PIC18F458
#word FSR = GETENV("SFR:FSR0L")
#byte POSTINC0 = GETENV("SFR:POSTINC0")
#else
#Error You need to setup the above for your PIC chip
#endif
void Saida(byte * data)
{
int8 count=121; //Why? you say the array is 244 bytes?
#asm
#if defined(__PCM__)
movf data, W // copy pointer to w reg..
movwf FSR // ..to pointer register
#elif defined(__PCH__)
movff data, FSR0L // copy low byte of pointer to low byte of pointer register 0..
movff &p_data+1, FSR0H // copy high byte of pointer to high byte of pointer register 0..
#else
#Error You need to setup the above for your PIC Chip
#endif
Loop: //must not be the same name as the function
#if defined(__PCM__)
movf INDF, W // load W with next databyte
incf FSR // do a 8-bit increment - increment indirection register to point to next databyte - for the next time
#elif defined(__PCH__)
movf POSTINC0, W // load w with next databyte and increment indirection register to point to next databyte - for the next time
#else
#Error You need to setup the above for your PIC Chip
#endif
movwf PORTB
decfsz count, F
goto loop // loop for next byte
#endasm |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19215
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| Posted: Thu Oct 04, 2018 11:51 am |
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OK. I've tweaked a couple of things and put it together with a basic demo:
| Code: |
#include <18F4550.h>
#fuses NOWDT, NOXINST
#use delay(internal=8MHz)
//Minimum processor setup
#byte PORTB=getenv("SFR:LATB")
// Setup Index Register locations (FSR and INDF)
#if defined(__PCM__) // For example (and tested on) PIC16F74, PIC16F887
#byte FSR = GETENV("SFR:FSR")
#byte INDF = GETENV("SFR:INDF")
#elif defined(__PCH__) // For example (and tested on) PIC18F458
#word FSR = GETENV("SFR:FSR0L")
#byte POSTINC0 = GETENV("SFR:POSTINC0")
#else
#Error You need to setup the above for your PIC chip
#endif
void Saida(byte * data)
{
int8 count=121; //Why? you say the array is 244 bytes?
FSR=data; //simplest way to load the FSR
#asm
Loop: //must not be the same name as the function
#if defined(__PCM__)
movf INDF, W // load W with next databyte
incf FSR // do a 8-bit increment - increment indirection register to point to next databyte - for the next time
#elif defined(__PCH__)
movf POSTINC0, W // load w with next databyte and increment indirection register to point to next databyte - for the next time
#else
#Error You need to setup the above for your PIC Chip
#endif
movwf PORTB
decfsz count, F
goto loop // loop for next byte
#endasm
}
void main(void)
{
unsigned int8 data_array[244] = {0,1,2,3,4,5,6,7,8,9,10,
0,1,2,3,4,5,6,7,8,9,10,
0,1,2,3,4,5,6,7,8,9,10,
0,1,2,3,4,5,6,7,8,9,10,
0,1,2,3,4,5,6,7,8,9,10,
0,1,2,3,4,5,6,7,8,9,10,
0,1,2,3,4,5,6,7,8,9,10,
0,1,2,3,4,5,6,7,8,9,10,
0,1,2,3,4,5,6,7,8,9,10,
0,1,2,3,4,5,6,7,8,9,10,
0,1,2,3,4,5,6,7,8,9,10,
0,1,2,3,4,5,6,7,8,9,10,
0,1,2,3,4,5,6,7,8,9,10,
0,1,2,3,4,5,6,7,8,9,10,
0,1,2,3,4,5,6,7,8,9,10,
0,1,2,3,4,5,6,7,8,9,10,
0,1,2,3,4,5,6,7,8,9,10,
0,1,2,3,4,5,6,7,8,9,10,
0,1,2,3,4,5,6,7,8,9,10,
0,1,2,3,4,5,6,7,8,9,10,
0,1,2,3,4,5,6,7,8,9,10,
0,1,2,3,4,5,6,7,8,9,10,
0,1 };
set_tris_b(0);
Saida(data_array);
while (TRUE)
;
}
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vtrx
Joined: 11 Oct 2017
Posts: 141
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| Posted: Thu Oct 04, 2018 12:40 pm |
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I'll be home at night.
I'll post the results. Thank you very much. |
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