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240 lines
7.3 KiB
Plaintext
240 lines
7.3 KiB
Plaintext
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Description of the C library for the cc65 C compiler
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(C) Copyright 1998-1999 Ullrich von Bassewitz
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(uz@musoftware.de)
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Contents
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--------
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1. Overview
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2. ISO C compatible library
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3. CPU specific stuff - 6502.h
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4. System specific stuff
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5. Direct console I/O - conio.h
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6. Using the joystick - joystick.h
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7. Bugs/Feedback
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8. Copyright
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1. Overview
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-----------
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This file contains a description of the library routines available for the
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cc65 C compiler. It is not complete in some areas, so if you miss
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something, have a look into the header files. All functions, that are not
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defined by the ISO C standard have a short comment in the headers,
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explaining their use.
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2. ISO C compatible library
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---------------------------
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The C library contains a large subset of the ISO C library. Functions are
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usually missing in areas, where there is no support on typical 6502
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systems. Wide character sets are an example for this.
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I will not go into detail about the ISO functions. If a function is not
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mentioned here explicitly, expect it to be available and to behave as
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defined in the C standard.
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Functions that are NOT available:
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* ftell/fseek/fgetpos/fsetpos
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* tmpfile/tmpnam
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* The scanf family of functions
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* time/asctime/ctime/difftime/asctime/gmtime/localtime/mktime/strftime
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* system
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* All functions that handle floating point numbers in some manner.
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* The div and ldiv functions (because cc65 is not able to return
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structs).
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* All functions handling wide character strings.
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* Signals and all related functions (having SIGSEGV would be cool:-)
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* rename/remove/rewind
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* setbuf/setvbuf/ungetc
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Functions that are limited in any way:
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* fopen/fread/fwrite/fclose/fputs/fgets/fscanf....
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These functions are built on open/read/write/close. Neither of these
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low level functions is currently available for the supported systems,
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and so, fopen and friends do not work. However, the functions exist
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and are tested to some degree under the ACE operating systems (which
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is no longer supported).
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* The va_... family of macros
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The macros do not work completely as defined by the standard. Since cc65
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has the wrong calling order, the (non-standard) va_fix macro must be used
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to access fixed parameters in functions with a variable parameter size.
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See newvers.txt for a discussion of the problem.
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* strcspn/strpbrk/strspn
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These functions have a length limitation of 256 for the second string
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argument. Since this string gives a character set, and there are only 256
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distinct characters, this shouldn't be a problem.
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* Since there is no such thing as an environment on all supported
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systems, the getenv function will always return a NULL pointer.
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* There is no other locale than the "C" locale. The native locale is
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identical to the "C" locale.
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In addition to these limitations, some more functions are limited if inlined
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versions are requested by using -Os:
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* The strlen function only works for strings with a maximum length of
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255 characters.
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* The isxxx character classification functions from <ctype.h> will give
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unpredictable results if the argument is not in character range
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(0..255). This limitation may be removed by #undef'ing the function
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name (when using -Os, the functions are actually macros that expand to
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inline assembler code, but the real functions are still available if
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the macro definition is removed).
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3. CPU specific stuff - 6502.h
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------------------------------
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The header file 6502.h contains some functions that make only sense with
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the 6502 CPU. Examples are macros to insert more or less useful
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instructions into your C code, or a function to call arbitrary machine
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language subroutines, passing registers in and out.
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4. System specific stuff
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------------------------
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For each supported system there's a header file that contains calls or
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defines specific for this system. So, when programming for the C64,
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include c64.h, for the C128, include c128.h and so on. To make the task
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for the Commodore systems easier, there is also a header file named cbm.h
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that will define stuff common for all CBM systems, and include the header
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file for the specific target system.
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The header files contain
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* Defines for special keys (like function keys)
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* Defines for special characters (like the graphics characters)
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* Variables with a fixed address in memory that may be used to access
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special hardware. For the C64 and C128 there is a variable struct
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named "sid". Writing to the fields of this struct will write to the
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SID device instead. Using these variables will make your program more
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readable and more portable. Don't fear ineffective code when using
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these variables, the compiler will translate reads and writes to these
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structs into direct memory accesses.
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* Other routines that make only sense for a specific system. One example
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are routines to write memory locations in the system bank for the CBM
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600/700 family (called B128/B256 in the US).
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5. Direct console I/O - conio.h
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-------------------------------
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The conio header file contains a large set of functions that do screen and
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keyboard I/O. The functions will write directly to the screen or poll the
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keyboard directly with no more help from the operating system than needed.
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This has some disadvantages, but on the other side it's fast and
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reasonably portable. conio implementations exist for the following
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targets:
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c64
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c128
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plus/4
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cbm610 (that is, the complete 600/700 series)
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pet (all PETs except the 2001)
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apple 2
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atari
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The conio.h header file does also include the system specific header files
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which define constants for special characters and keys.
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6. Using the joystick - joystick.h
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----------------------------------
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For systems that have a joystick, joystick.h will define a subroutine to
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read the current value, including constants to evaluate the result of this
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function. To help in writing portable code, the header file will define
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the symbol __JOYSTICK__ on systems that have a joystick.
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7. Bugs/Feedback
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----------------
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If you have problems using the library, if you find any bugs, or if you've
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written some extensions or otherwise interesting programs, I would be glad
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to hear from you. Feel free to contact me by email (uz@musoftware.de).
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8. Copyright
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------------
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This C runtime library implementation for the cc65 compiler is (C)
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Copyright 1998-1999 Ullrich von Bassewitz. For usage of the binaries
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and/or sources the following conditions do apply:
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This software is provided 'as-is', without any expressed or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not
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be misrepresented as being the original software.
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3. This notice may not be removed or altered from any source
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distribution.
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