DEFF3.TXT --------- I have given, below, a description of each of the functions which I have written for the file - DEFF3.C and which may be accessed through - DEFF3(.CRL) when you use the CLINK function with BDS C. It is not necessary to specify "DEFF3" on the command line as BDS C will look for any missing functions in the DEFF files, automatically, in answer to a RETURN entered when it asks you for instructions as to which CRL files it should search for the missing functions. If you intend to use DEFF3 in this way then it should be on the same disk as the BDS C DEFF files. Now, the functions I have written and what they do are - BITCOUNT(n) unsigned n; ---------- Returns the number of set bits ( = 1) in a byte. BINARY(x, v, n) int x, v[], n; --------------- Checks whether a binary number (x) occurs in a sorted array (v, of n elements) and, if so, returns the binary number or else returns -1 if it doesn't occur. CGET() ------ Similar to "getchar" in what it does except that it will read ANY byte value from the console. i.e. the value you enter doesn't have to be either ASCII or printable. It returns the value of the byte entry. CLOSE_FILE(fcb) char fcb[36]; --------------- This will close the file whose name is included in the file control block pointed to by "fcb". It is the companion function to "OPEN_FILE" and should be used to close any file previously opened with OPEN_FILE. It returns the same values as OPEN_FILE. CLRSCREEN() ----------- Will clear the screen and home the cursor, using in-built terminal software commands. It is (probably) only usable by Hazeltine family terminals but could be altered to suit other terminals provided you know the byte value(s) to send to the terminal to activate the clear screen/home function. Doesn't return anything. CON_STAT() ---------- This checks the console status and returns ZERO if there is no character waiting, else it returns 0xff....NOT the character itself. It is a useful function for those inputs where you tell the user - "Enter any character to continue." CPUT(c) int c; ------- Similar to "putchar" except that it will send ANY byte value to the console. Naturally the console will only display the "visible" characters. Doesn't return anything useful. CREATE_FILE(fcb) char fcb[36]; ---------------- This will create the file named in the file control block (see open_file for a description of this) an initialise it for both read and write functions. Note particularly that it doesn't check to see whether a file of this name already exists so you need to do this independently if you want to make sure you haven't got two files of the same name in the disk directory. It is supposed to return 0xff (255 decimal) if the disk is full and the name can't be created, but I'm not so sure that you can rely on it to do so. Probably the best way to be sure is to now try to open the file (with open_file) and see what happens then. DIRECTC(duty) int duty; ------------- This is CP/M function No. 6 and it can be used to either get a character from the terminal, or to send a character to the console. It depends on the value of "duty" which should be either - 0xff for input from the terminal or the byte value for output to the console It returns the input character in the first case or zero in the second case. ERASE_FILE(fcb) char fcb[36]; --------------- Erases from the directory the name of the file in the file control block. For a description of this see open_file. It will return 0xff if the file isn't found. GET_CPM() --------- Returns a 16-bit number (in HL) with the details - H = 0x00 for CP/M OR H = 0x01 for MP/M L = 0x00 for all releases prior to 2.0 L = 0x20 for version 2.0, 0x21 for version 2.1, 0x22 for version 2.2, and so on. If you want to use any of this information then you will need to mask off H (or L) to find out what it was the function returned. GET_DEFAULT() ------------- Returns the name for the current default disk. Note A = 0, B = 1....and so on. GET_IOBYTE() ------------ Returns the current IOBYTE setting under CP/M 2.2. INDEX(s, t) char s[], t[]; ------------- Returns a pointer to the position of string "t" inside string "s", else returns -1 if no match is found. ITOA(n, str) int n; char s[]; ------------ Will convert an integer (n) into a printable ASCII string, which is placed in "str". This is one of the obvious functions which should already have been included in BDS C. ISALNUM(c) char c; ---------- Returns TRUE/FALSE whether the character is alpha-numeric. MAKE_RO() --------- Makes the current logical disk read-only status. I don't think it returns anything. OPEN_FILE(fcb) char fcb[36]; -------------- Opens the nominated file, the name of which must be in the file control block ("fcb") in the manner required by CP/M. Note that the file is opened for BOTH reading and writing. Before using this function you should have already made a file control block with the function - setfcb(fcb, filename) Note particularly "fcb" as used in these functions is a pointer to the file control block or, as used in assembly language programming, it is the address of the fcb which holds the file name. This should be an external buffer so that it is known to all functions in the programme. This will return 0xff if the open was unsuccessful or a number 0, 1, 2 or 3 (which is an offset into the DMA buffer) if the open succeeded. For those who understand the way CP/M works, this offset may be used to get the directory entry information on the opened file. To be able to access the DMA buffer you must have first created a DMA buffer whose address (the pointer to) is known to you. Do this with the function - set_dma(dma) int dma[128]; PRINT_DEC(n) int n; ------------ Prints a decimal number (n) to the console. PRT_STR(str) char *str; ------------ Prints a string (terminated by the character "$") to the console. Doesn't return anything. Note you shouldn't use this function if you expect to meet with the dollar sign other than as the end of line marker. READ_SEQ_SEC(fcb) char fcb[36]; ----------------- Starting from the first available sector (of 128 bytes) it will reach each successive sector in the file until the end of the file is reached. Returns zero when the read is successful, else returns a non-zero number. Note that the file must already have been opened prior to this function being called. READ_STR(str) char *str; ------------- Will read a RETURN-terminated string from the terminal and place it, as a NULL-terminated string, into the str buffer. Note, when calculating the size of the string buffer you will use, you have to add one for the '\0' character which will terminate the string. e.g. if you want the maximum length of the string to be 80 characters then specify - char str[81]; for the string buffer. RESET_DSK() ----------- This resets the disk system and reads the active disk details into memory again. It is typically used in a programme after a disk has been changed, or swapped. It doesn't return anything. REVERSE(str) char str[]; ------------ Will reverse a null-terminated string in place. SEARCH_FIRST(fcb) char fcb[36]; ----------------- This searches the disk directory for the first file name which matches the name given in the file control block pointed to by "fcb". Note - see OPEN_FILE for a run-down on the file control block under CP/M. The file name you choose may be either ambiguous or specific. If it is ambiguous, this function will return the first file name which matches the given name. When a match has occurred, it returns 0, 1, 2 or 3 which is the offset into the DMA buffer where the directory information has been placed by CP/M. Knowing the offset (which is a factor of 32 bytes) you can now recover the actual directory entry as stored by CP/M. e.g. if the offset is, say, 2 then if you look 2 x 32 = 64 bytes into the DMA you will find the first byte of the directory entry for the matching file name. If it returns 0xff (255 decimal) then you didn't find any file which matched the name you gave. SEARCH_NEXT() ------------- Carries on from search_first to locate any further names which match the name in the file control block. Note this can only be used after a successful search_first. It will return the same parameters as search_first for both failure and success. SELECT_DSK(drive) int drive; ----------------- This allows you to change the "logical" drive during the course of a programme. Just enter the drive name as A, B, C...M, etc and the function converts this to the value required by CP/M. Doesn't return anything. SET_ATTRIBUTES(fcb) char fcb[36]; ------------------- Used to set (or re-set) the attributes for R/O, R/W, DIR, SYS and ARC and CPY (in my backup programme) so that CP/M will know how to deal with a particular file in the disk directory. To use this function successfully you must have first formulated a file control block with the bits you want CP/M to recognise either set ( = 1) or re-set to zero, as the case may be. Will return 0xff if the file can't be located in the disk directory. SET_DMA(buffer) int buffer[128]; --------------- Creates a pointer to the DMA (CP/M's direct memory address) buffer which can then be used in the read/write and other CP/M functions where a DMA is required. It is probably most useful when "buffer" is declared externally. SET_IOBYTE(iob) int iob; --------------- Re-sets the IOBYTE to the specified value. Doesn't return anything. SHELL_SORT(v, n) int v[], n; --------------- Sorts an array "v" of "n" elements into increasing order. SWAP_POINTERS(px, py) char *px[], *py[]; --------------------- Will interchange two pointers. USER_ID(code) int code; ------------- Will either return the current User Number, if code = 255 (0xff), or will change the User Number if code = 0 to 15. WRITE_SEQ_SEC(fcb) char fcb[36]; ------------------ A companion function to read_seq_sec. This will write successive sectors to the open file named in the file control block. It will return zero if successful or a non-zero number if not successful in completing the write. ed by CP/M. Doesn't ret