Cortex-A8 Technical Reference Manual - ARM Information Center

Address
of object
Table 12-60 shows some examples.
Example 12-9 shows the code for setting a simple unaligned watchpoint.
Debug
Example 12-9 Setting a simple unaligned watchpoint
bool SetSimpleWatchpoint(int watch_num, uint32 address, int size)
{
// Step 1. Disable the watchpoint being set.
WriteDebugRegister(112 + watch_num, 0x0);
// Step 2. Write addresses to the WVRs, leaving the bottom 3 bits zero.
WriteDebugRegister(96 + watch_num, (address & 0xFFFFFF8));
// Step 3. Determine the byte address select value to use.
byte_address_select := (1'b1 3));
}
// Step 6. Return flag to caller indicating if second watchpoint was used.
return (byte_address_select >= 9'b100000000)
}
12.11.3 Single-stepping
Object size
in bytes
Table 12-60 Example byte address masks for watchpointed objects
First address
value
First byte address
mask
Second address
value
0x00008000 1 0x00008000 b00000001 Not required -
0x00008007 1 0x00008000 b10000000 Not required -
0x00009000 2 0x00009000 b00000011 Not required -
0x0000900c 2 0x00009000 b11000000 Not required -
Second byte
address mask
0x0000900d 2 0x00009000 b10000000 0x00009008 b00000001
0x0000A000 4 0x0000A000 b00001111 Not required -
0x0000A003 4 0x0000A000 b01111000 Not required -
0x0000A005 4 0x0000A000 b11100000 0x0000A008 b00000001
0x0000B000 8 0x0000B000 b11111111 Not required -
0x0000B001 8 0x0000B000 b11111110 0x0000B008 b00000001
You can use the breakpoint mismatch bit to implement single-stepping on the processor. Unlike
high-level stepping, single-stepping implements a low-level step that executes a single
instruction at a time. With high-level stepping, the instruction is decoded to determine the
address of the next instruction and a breakpoint is set at that address.
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