6.8. BACKWARD: Using Byte Manipulations
We now develop a somewhat more complex program that uses the capability just illustrated to obtain and print characters. The BACKWARD program (Figure 6-8) obtains and stores a line of text. It then accesses the stored bytes in such a way as to reverse their order completely. Input such as evil will be printed as live.
Figure 6-8. BACKWARD: An illustration of accessing bytes
// BACKWARD Print a string backwards // This program pauses for the user to enter a line // of text, and prints that text backwards. NL = 0xa // Newline character LEN = 96 // Line length allowed .global chrget,chrput // External references .type chrget,@function // and their .type chrput,@function // types .data // Declare storage .align ...