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45 lines
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45 lines
1.8 KiB
ReStructuredText
.. _debugger-expressions-list:
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Debugger Expressions Guide
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==========================
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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.
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| ( ) : standard parentheses
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| ++ -- : postfix increment/decrement
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| ++ -- ~ ! - + b@ w@ d@ q@ : prefix inc/dec, binary NOT, logical NOT, unary +/-, memory access
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| * / % : multiply, divide, modulus
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| + - : add, subtract
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| << >> : shift left/right
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| < <= > >= : less than, less than or equal, greater than, greater than or equal
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| == != : equal, not equal
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| & : binary AND
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| ^ : binary XOR
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| | : binary OR
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| && : logical AND
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| || : logical OR
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| = \*= /= %= += -= <<= >>= &= \|= ^= : assignment
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| , : separate terms, function parameters
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Differences from C Behaviors
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----------------------------
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- First, all math is performed on full 64-bit unsigned values, so things like a < 0 won't work as expected.
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- Second, the logical operators && and || do not have short-circuit properties -- both halves are always evaluated.
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- Finally, the new memory operators work like this:
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- b@<addr> refers to the byte read from <addr>.
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- Similarly, w@ refers to a word in memory, d@ refers to a dword in memory, and q@ refers to a qword in memory.
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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'. So dw\@300 refers to data memory word at address 300 and id\@400 refers to an I/O memory dword at address 400.
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