Memory corruption, address errors, and illegal instruction errors are generally caused by use of an uninitialized, incorrectly initialized, or already freed/closed pointer or memory. You may be using the pointer directly, or it may be one that you placed (or forgot to place) in a structure passed to system calls. Or you may be overwriting one of your arrays, or accidentally modifying or incrementing a pointer later used in a free/close. Be sure to test the return of all open/allocation type functions before using the result, and only close/free things that you successfully opened/allocated. Use watchdog/torture utilities such as Enforcer and MungWall in combination to catch use of uninitialized pointers or freed memory, and other memory misuse problems. Use the debugging tool TNT to get additional debugging information instead of a Software Error requester. You may also be overflowing your stack--your compiler's stack checking option may be able to catch this. Cut stack usage by dynamically allocating large structures, buffers, and arrays which are currently defined inside your functions. Corruption or crashes can also be caused by passing wrong or missing arguments to a system call (for example SetAPen(3) or SetAPen(win,3), instead of SetAPen(rp,3)). C programmers should use function prototypes to catch such errors. If using short integers be sure to explicitly type long constants as long (e.g., 42L). (For example, with short ints, 1 << 17 may become zero). If corruption is occurring during exit, use printf() (or KPrintF(), etc.) with Delay(n) to slow down your cleanup and broadcast each step. A bad pointer that causes a system crash will often be reported as an standard 680x0 processor exception $00000003 or 4, or less often a number in the range of $00000006-B. Or an Amiga-specific alert number may result. See <exec/alerts.h> for Amiga-specific alert numbers. Also see "Crashes--After Exit" below.
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