ARM r1p3, R4, R4F

Debug

ID013010 Non-Confidential, Unrestricted Access

{

return false;

}

Note

You can use a similar sequence to read a halfword of memory and to write to memory.

To read or write blocks of memory, substitute the data instruction with one that uses

post-indexed addressing. For example:

LDRB R1, [R0],1

This prevents reloading the address value for each sequential word.

Example 11-20 shows the code for reading a block of bytes of memory.

Example11-20 Reading a block of bytes of memory

ReadBytes(uint32 address, bool &aborted, uint8 *data, int nbytes)

{

// Step 1. Save the value of R0 and R1.

saved_r0 := ReadRegister(0);

saved_r1 := ReadRegister(1);

// Step 2. Write the address to R0

WriteRegister(0, address);

while (nbytes > 0)

{

// Step 3. Execute instruction LDRB R1,[R0],1 through the ITR.

ExecuteARMInstruction(0xE4D01001);

// Step 4. Read the value of R1 that contains the data at the

// address.

*data++ := ReadRegister(1);

--nbytes;

}

// Step 5. Restore the corrupted registers R0 and R1.

WriteRegister(0, saved_r0);

WriteRegister(1, saved-r1);

// Step 6. Check the DSCR for a sticky abort.

aborted := CheckForAborts();

return datum;

}

Example 11-21 shows the sequence for reading a word of memory.

Note

A faster method is available for reading and writing words using the direct memory access

function of the DCC. See Fast memory read/write on page11-68.

Example 11-21 Reading a word of memory

uint32 ReadWord(uint32 address, bool &aborted)

{

// Step 1. Save the value of R0.

saved_r0 := ReadRegister(0);