Description
Some users find their (constant) jump tables get placed in RAM (in RW data) rather than ROM (constdata), using code like this:

typedef void PFUNC(void);
const PFUNC *table[3] = {func0, func1, func2}; 

Solution
This typedef is incorrect for this purpose. It should read something like:

typedef void (*PFUNC)(void); 

The PFUNC type is a pointer to a void function that has no parameters. This can then be used to create an array of constant function pointers as follows:

const PFUNC table[] = {func0, func1, func2}; 

The following example shows this in full:

extern void func0(void);
extern void func1(void);
extern void func2(void); 

typedef void (*PFUNC)(void);
const PFUNC table[] = {func0, func1, func2}; 

void jump(unsigned i)
{
  if (i <=2)
    table[i]();
} 

If this is compiled, then disassembled with:

armcc -c jump.c
decaof -c jump.o 

the table[] has been placed in a read only C$$constdata area, and so can then be placed in ROM as required.

** Area C$$code, Alignment 4, Size 20 (0x0014), 1 relocations
        Attributes: Code{32bit,FPIS3}: Read only
  EXPORT jump
jump
  0x000000: CMP r0,#2
  0x000004: MOVHI pc,lr
  0x000008: LDR r1,0x10
  0x00000c: LDR pc,[r1,r0,LSL #2]
  0x000010: 00000000 literal pool 

** Area C$$constdata, Alignment 4, Size 12 (0x000c), 3 relocations
Attributes: Data: Read only 

After linking, the literal pool will contain the address of the table in ROM.