//    Upper bytes are junk.
//  - *const instructions may use a constant larger than the instruction can encode.
//    In this case the assembler expands to multiple instructions and uses tmp
//    register (R27).
//  - All 32-bit Ops will zero the upper 32 bits of the destination register.

// Suffixes encode the bit width of various instructions.
// D (double word) = 64 bit
// W (word)        = 32 bit
// H (half word)   = 16 bit