Phrase Strings stored in rom

[thgood]

Hello,

I want to index into a large number strings stored in ROM. Each string will be 32 characters long. There will be about 50 strings.

I have run into problems using the built in CCS arrays. What is the best alternative for coding this up and accessing the strings randomly?



Thanks

Tom

[Ttelmah]

[Guest]

[Ttelmah]

[burnsy]

here's a copy of my reply in a similar discussion....

/*

This might help. I will try and remember how it works....

I needed to to store strings to display on an lcd. All my strings were of fixed length (16 bytes).. If each character was only 7bits long, you fit two in each word. I would store them like this..


// Note Exchange2
#define LCDMSG_PWRUPMSG0 0x00
#rom 0x0100={0x104E,0x37F4,0x32A0,0x22F8,0x31E8,0x30EE,0x33E5,0x1920}

// V1.58
#define LCDMSG_PWRUPMSG1 0x01
#rom 0x0108={0x1020,0x1020,0x1056,0x18AE,0x1AB8,0x1020,0x1020,0x1020}

// INSERT NOTES
#define LCDMSG_INSERTN 0x02
#rom 0x0110={0x1020,0x24CE,0x29C5,0x2954,0x104E,0x27D4,0x22D3,0x1020}

Each msg would have a number, and a fixed starting address. All you do is calc the starting address to retrieve the string.

eg

void
wr_line2lcd(uchar x)
{
uchar u;
uint t;
/* wr lcd direct with byte, with bytes stored in flash */
/* calc offset to msg (16 bytes per msg) */
t = x;
t <<= 3;
t += LCD_MSGS; /* offset to table in rom */

/* copy each byte to lcd_putchar() */
for (u = 0 ; u < 0x10 ; u++ )
{
/* first byte */
x = read_flash(t + u,0);
lcd_putchar(x);
/* second byte */
x = read_flash(t + u,1);
lcd_putchar(x);
}
}

if you want fixed string lenghts or not, here is a handy VB utility I wrote that will allow you to type in a string and it will convert the string into ROM = (xxxxh,xxxxxh....) code for you. Follow the link.

http://home.iprimus.com.au/jtek/pic/stringtorom14.exe

hope this helps

*/
_________________
This is the last code change until its ready....