I've got a real strange problem with a ROM array in C18. Can anyone tell
me what I'm doing wrong? It seems that if I use a literal for the first
array index, I get back the right value. If I use a variable, I get back
the wrong value. Here's the code:

void LcdDrawChar(unsigned char x, unsigned char y, unsigned char
AsciiChar){
// Draw a character from bitmap using LCD bit set and bit clear commands.
Assumes use of 5x7 bitmap in
// charset5x7. Bitmap of char is similar to lcd in that lsb is leftmost
pixel.
static unsigned char rc;                                // Row and column counters for where we are
in drawing the character
static unsigned char cc;
static unsigned char hhdebug1, hhdebug2, hhdebug3;
static unsigned char RowBits;                                   // pixel map for a row
static unsigned char CharSetIndex;              // Precalculate the index into the
character map
hhdebug1=AsciiChar;
CharSetIndex=AsciiChar-0x20;                            // Precalculate the index into the
character map
for(rc=0; rc<7; rc++){                          // for each row in the character
  RowBits=charset5x7[CharSetIndex][rc];         // Get bitmap for this row
  hhdebug2=charset5x7[0x14][rc];
  for(cc=0; cc<5; cc++){                        // for each col in the character
    LcdSetBit(x+cc, y+rc,RowBits & 0x01);       // Set or clear pixel based on
lsb of row
    RowBits=RowBits>>1;                         // Shift to right to get next col in lsb
  }
}
}

        I made the variables static so I can watch them in the watch window. The
line that starts with RowBits sets RowBits to 0xff (the wrong answer)
according to the watch window. The next line sets hhdebug2 to 0x08, the
right answer. The watch window shows that CharSetIndex is 0x14, so I'd
expect these two lines to return the same (right) answer.
        The charset5x7 is defined as:

// 5x7 font in 7 8-bit bytes. Leftmost pixel is lsb.
rom const char charset5x7[][7] ={
{
0b00000000,             // 0x20 space
0b00000000,
0b00000000,
0b00000000,
0b00000000,
0b00000000,
0b00000000},
{
0b00000100,             // 0x21 !
0b00000100,
0b00000100,
0b00000100,
0b00000000,
0b00000000,
0b00000100},
{
0b00001010,             // 0x22  "
0b00001010,
0b00001010,
0b00000000,
0b00000000,
0b00000000,
0b00000000},
{
0b00001010,             // 0x23 #
0b00001010,
0b00011111,
0b00001010,
0b00011111,
0b00001010,
0b00001010},
{
0b00000100,             // 0x24 $
0b00011110,
0b00000101,
0b00001110,
0b00010100,
0b00001111,
0b00000100},
{
0b00000011,             // 0x25 %
0b00010011,
0b00001000,
0b00000100,
0b00000010,
0b00011001,
0b00011000},
{
0b00000110,             // 0x26 &
0b00001001,
0b00000101,
0b00000010,
0b00000101,
0b00001001,
0b00000110},
{
0b00001110,             // 0x27 '
0b00001000,
0b00000100,
0b00000000,
0b00000000,
0b00000000,
0b00000000},
{
0b00000100,             // 0x28 (
0b00000010,
0b00000001,
0b00000001,
0b00000001,
0b00000010,
0b00000100},
{
0b00000010,             // 0x29 )
0b00000100,
0b00001000,
0b00001000,
0b00001000,
0b00000100,
0b00000010},
{
0b00000000,             // 0x2A *
0b00000100,
0b00010101,
0b00001110,
0b00010101,
0b00000100,
0b00000000},
{
0b00000000,             // 0x2B +
0b00000100,
0b00000100,
0b00011111,
0b00000100,
0b00000100,
0b00000000},
{
0b00000000,             // 0x2C ,
0b00000000,
0b00000000,
0b00000000,
0b00000110,
0b00000100,
0b00000010},
{
0b00000000,             // 0x2D -
0b00000000,
0b00000000,
0b00011111,
0b00000000,
0b00000000,
0b00000000},
{
0b00000000,             // 0x2E .
0b00000000,
0b00000000,
0b00000000,
0b00000000,
0b00000110,
0b00000110},
{
0b00000000,             // 0x2f /
0b00010000,
0b00001000,
0b00000100,
0b00000010,
0b00000001,
0b00000000},
{
0b00001110,             // 0x30 0
0b00010001,
0b00011001,
0b00010101,
0b00010011,
0b00010001,
0b00001110},
{
0b00000100,             // 0x31 1
0b00000110,
0b00000100,
0b00000100,
0b00000100,
0b00000100,
0b00001110},
{
0b00001110,             // 0x32 2
0b00010001,
0b00010000,
0b00001000,
0b00000100,
0b00000010,
0b00011111},
{
0b00011111,             // 0x33 3
0b00001000,
0b00000100,
0b00001000,
0b00010000,
0b00010001,
0b00001110},
{
0b00001000,             // 0x34 4
0b00001100,
0b00001010,
0b00001001,
0b00011111,
0b00001000,
0b00001000},
{
0b00011111,             // 0x35 5
0b00000001,

and continues on  Note that the entry for 0x34 (actually 0x14 since we
subtract 0x20) is indeed 0x08, as returned by the array reference with
the constant.

        Any ideas???


Thanks!

Harold



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