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; Split string function development testbed
;
; The split function is a reusable function for the string library of
; the monitor. It splits a string into substrings using a delimiter character.
;
; Contains a reusable function, e.g. for the string library of the monitor.
; originally developed for the FAT32 implementation
;
; done by sy2002 in July 2016
#include "../dist_kit/sysdef.asm"
#include "../dist_kit/monitor.def"
.ORG 0x8000
MOVE STR_TITLE, R8
SYSCALL(puts, 1)
; read string
MOVE STR_STRING, R8
SYSCALL(puts, 1)
MOVE STRBUFFER, R8
SYSCALL(gets, 1)
SYSCALL(crlf, 1)
; read delimiter
MOVE STR_DELIMITER, R8
SYSCALL(puts, 1)
SYSCALL(getc, 1)
SYSCALL(putc, 1)
SYSCALL(crlf, 1)
MOVE R8, R7
; stack pointer before
MOVE STR_STACK_BEGIN, R8
SYSCALL(puts, 1)
MOVE SP, R8
SYSCALL(puthex, 1)
SYSCALL(crlf, 1)
; split string and output amount of substrings
MOVE R7, R9
MOVE STRBUFFER, R8
RSUB SPLIT, 1
MOVE R8, R7 ; R7 = amount of substrings
MOVE STR_SUBSTRINGS, R8
SYSCALL(puts, 1)
MOVE R7, R8
SYSCALL(puthex, 1)
SYSCALL(crlf, 1)
; save SP
MOVE SP, R1 ; R1 = SP after split call
; no substrings at all (pure delimiter string)
CMP R7, 0
RBRA RESTORE_STACK, Z
; output substrings
MOVE 1, R0 ; R0 = string counter
NEXT_SUBSTR MOVE STR_SUBSTR, R8
SYSCALL(puts, 1)
MOVE R0, R8
SYSCALL(puthex, 1)
MOVE STR_SUBSTRLEN, R8
SYSCALL(puts, 1)
MOVE @SP++, R8
MOVE R8, R6 ; R6 = substring length
SYSCALL(puthex, 1)
MOVE STR_SUBSTRSTART, R8
SYSCALL(puts, 1)
MOVE SP, R8
SYSCALL(puts, 1)
SYSCALL(crlf, 1)
ADD R6, SP ; next string in memory frame
ADD 1, R0 ; increase string counter
SUB 1, R7 ; decrease substring amount
RBRA NEXT_SUBSTR, !Z
; restore stack pointer
RESTORE_STACK MOVE R1, SP
ADD R9, SP
; stack pointer after
MOVE STR_STACK_AFTER, R8
SYSCALL(puts, 1)
MOVE SP, R8
SYSCALL(puthex, 1)
SYSCALL(crlf, 1)
SYSCALL(exit, 1)
STR_TITLE .ASCII_P "\n"
.ASCII_P "Split string development testbed - done by sy2002 in July 2016\n"
.ASCII_W "==============================================================\n\n"
STR_STRING .ASCII_W "Enter a string: "
STR_DELIMITER .ASCII_W "Enter a delimiter: "
STR_SUBSTRINGS .ASCII_W "Substrings found: "
STR_SUBSTR .ASCII_W "Substring #"
STR_SUBSTRLEN .ASCII_W " Length: "
STR_SUBSTRSTART .ASCII_W ": "
STR_STACK_BEGIN .ASCII_W "SP before: "
STR_STACK_AFTER .ASCII_W "SP after: "
;=============================================================================
; REUSABLE CODE STARTS HERE
;=============================================================================
;
;*****************************************************************************
;* SPLIT splits a string into substrings using a delimiter char
;*
;* Returns the substrings on the stack, i.e. after being done, you need to
;* add the amount of words returned in R9 to the stack pointer to clean
;* it up again and not leaving "memory leaks".
;*
;* The memory layout of the returned area is:
;* <size of string incl. zero terminator><string><zero terminator>
;*
;* The strings are returned in positive order, i.e. you just need to add
;* the length of the previous string to the returned string pointer
;* (i.e. stack pointer) to jump to the next substring from left to right.
;*
;* INPUT: R8: pointer to zero terminated string
;* R9: delimiter char
;* OUTPUT: SP: stack pointer pointer to the first string
;* R8: amount of strings
;* R9: amount of words to add to the stack pointer to restore it
;*****************************************************************************
;
SPLIT INCRB
MOVE @SP++, R0 ; save return address and
; delete it by adding 1
; find the end of the string, R1 will point to it
MOVE 1, R2
MOVE R8, R1
_SPLIT_FE CMP @R1, 0
RBRA _SPLIT_FE2, Z
ADD R2, R1
RBRA _SPLIT_FE, 1
_SPLIT_FE2 MOVE R1, R2 ; R2 = end of current substr
XOR R6, R6 ; R6 = amount of strings
XOR R7, R7 ; R7 = amount of words for R9
; skip empty string
CMP R8, R1
RBRA _SPLIT_ES_END, Z
; find the first occurrence of the delimiter
_SPLIT_FD CMP @--R1, R9 ; check for delimiter, mv left
RBRA _SPLIT_SS, Z ; yes, delimiter found
CMP R1, R8 ; beginning of string reached?
RBRA _SPLIT_SS, Z
RBRA _SPLIT_FD, 1
; copy substring on the stack, if it is at least one
; non-delimiter character
_SPLIT_SS MOVE R2, R3
SUB R1, R3 ; length of substring w/o zero
CMP R3, 1 ; only one character?
RBRA _SPLIT_SSB, !Z ; no: go on
CMP @R1, R9 ; only one char and char=delim
RBRA _SPLIT_SS_SKP, Z ; yes: skip
_SPLIT_SSB ADD 1, R6 ; one more string
SUB R3, SP ; reserve memory on the stack
SUB 2, SP ; size word & zero terminator
ADD R3, R7 ; adjust amount of words ..
ADD 2, R7 ; .. equally to stack usage
CMP @R1, R9 ; first char delimiter?
RBRA _SPLIT_SS_BGN, !Z ; no: go on
ADD 1, SP ; yes: adjust stack usage ..
SUB 1, R7 ; .. and word counter ..
SUB 1, R3 ; .. and reduce length ..
ADD 1, R1 ; .. and change start
_SPLIT_SS_BGN MOVE R1, R4 ; R4 = cur. char of substring
MOVE SP, R5 ; R5 = target memory of char
MOVE R3, @R5 ; save size w/o zero term.
ADD 1, @R5++ ; adjust for zero term.
_SPLIT_SS_CPY MOVE @R4++, @R5++ ; copy char
SUB 1, R3 ; R3 = amount to be copied
RBRA _SPLIT_SS_CPY, !Z
MOVE 0, @R5 ; add zero terminator
_SPLIT_SS_SKP MOVE R1, R2 ; current index = new end
CMP R1, R8 ; beginning of string reached?
RBRA _SPLIT_FD, !Z
_SPLIT_ES_END MOVE R6, R8 ; return amount of strings
MOVE R7, R9 ; return amount of bytes
MOVE R0, @--SP ; put return address on stack
DECRB
RET
;=============================================================================
; REUSABLE CODE ENDS HERE
;=============================================================================
STRBUFFER .BLOCK 1c2ab8222cThis file is pinned to the selected release. Download the original to open it in your design tool.