Debugger Expressions Guide¶
Expressions can be used anywhere a numeric parameter is expected. The syntax for expressions is very close to standard C-style syntax with full operator ordering and parentheses. There are a few operators missing (notably the trinary ? : operator), and a few new ones (memory accessors). The table below lists all the operators in their order, highest precedence operators first.
Numbers are prefixed according to their bases:
- Hexadecimal (base-16) numbers are prefixed with
- Decimal (base-10) numbers are prefixed with
- Octal (base-8) numbers are prefixed with
- Binary (base-2) numbers are prefixed with
- Unprefixed numbers are hexadecimal (base-16).
123is 123 hexadecimal (291 decimal).
$123is 123 hexadecimal (291 decimal).
0x123is 123 hexadecimal (291 decimal).
#123is 123 decimal.
0o123is 123 octal (83 decimal).
0b1001is 9 decimal.
Differences from C Behaviors¶
First, all math is performed on full 64-bit unsigned values, so things like a < 0 won’t work as expected.
Second, the logical operators && and || do not have short-circuit properties – both halves are always evaluated.
Finally, the new memory operators work like this:
b!<addr> refers to the byte at <addr> but does NOT suppress side effects such as reading a mailbox clearing the pending flag, or reading a FIFO removing an item.
b@<addr> refers to the byte at <addr> while suppressing side effects.
Similarly, w@ and w! refer to a word in memory, d@ and d! refer to a dword in memory, and q@ and q! refer to a qword in memory.
The memory operators can be used as both lvalues and rvalues, so you can write b@100 = ff to store a byte in memory. By default these operators read from the program memory space, but you can override that by prefixing them with a ‘d’ or an ‘i’.
As such, dw@300 refers to data memory word at address 300 and id@400 refers to an I/O memory dword at address 400.