ARM Compiler toolchain v4.1 for µVision Using the Compiler

Using the Inline and Embedded Assemblers of the ARM Compiler
7.37 Differences between expressions in embedded assembler and C or C++
The following differences exist between embedded assembly and C or C++:
• Assembler expressions are always unsigned. The same expression might have different
values between assembler and C or C++. For example:
MOV r0, #(-33554432 / 2) // result is 0x7f000000 MOV r0, #__cpp(-33554432 /
2) // result is 0xff000000
• Assembler numbers with leading zeros are still decimal. For example:
MOV r0, #0700 // decimal 700 MOV r0, #__cpp(0700) //
octal 0700 == decimal 448
• Assembler operator precedence differs from C and C++. For example:
MOV r0, #(0x23 :AND: 0xf + 1) // ((0x23 & 0xf) + 1) => 4 MOV r0, #__cpp(0x23 &
0xf + 1) // (0x23 & (0xf + 1)) => 0
• Assembler strings are not NUL-terminated:
DCB "Hello world!"
// 12 bytes (no trailing NUL) DCB __cpp("Hello
world!")
// 13 bytes (trailing NUL)
Note
The assembler rules apply outside __cpp, and the C or C++ rules apply inside __cpp.
7.37.1 See also
Concepts
• Access to C and C++ compile-time constant expressions from embedded assembler on
page 7-43
• Compiler support for embedded assembler on page 7-36.
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