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#ifndef included_formatstr
#define included_formatstr
; This routine for taking a base-10 exponent and a string of digits and (without
; a decimal) and inserting a decimal, any leading zeros, stripping trailing
; zeros, and appending an exponent if needed.
; Define the absolute maximum number of digits in the result string.
; If FORMAT_LEN is bigger than this value, then it will be reduced.
#ifndef MAX_FORMAT_LEN
#define MAX_FORMAT_LEN 19
#endif
; Define this to use an external reference to get the number of digits used
;#define EXTERNAL_FORMAT_LEN <pointer>
;
; For example, TI-OS has a byte at fmtDigits:
;#define EXTERNAL_FORMAT_LEN fmtDigits
; This is the max number of digits in the output.
; If EXTERNAL_FORMAT_LEN is used and it is 0, then this will be used.
#ifndef FORMAT_LEN
#define FORMAT_LEN 18
#endif
; Define this to use an external reference for the max exponent before switching
; to enginieering mode.
;#define EXTERNAL_FORMAT_MAX_ENGINEERING <pointer>
; Define the max exponent to use before switching to engineering format
; If none is defined, this uses FORMAT_LEN.
; If EXTERNAL_FORMAT_MAX_ENGINEERING is used and is 0 or larger than FORMAT_LEN,
; then this will be used.
;#define FORMAT_MAX_ENGINEERING
; Define this to use an external reference for the min exponent before switching
; to enginieering mode.
;#define EXTERNAL_FORMAT_MIN_ENGINEERING <pointer>
; Define the largest negative exponent to use engineering format
; If EXTERNAL_FORMAT_MIN_ENGINEERING is used and is 0 or larger than FORMAT_LEN,
; then this will be used.
#ifndef FORMAT_MIN_ENGINEERING
#define FORMAT_MIN_ENGINEERING -5 ; causes exponent of -5 to be enginierring
#endif
; For formatting, we need to define these three characters
; "Enginieering e" for values like "1.23456e10"
#ifndef TOK_ENG
#define TOK_ENG 'e'
#endif
; Negative sign
#ifndef TOK_NEG
#define TOK_NEG '-'
#endif
; Decimal point
#ifndef TOK_DECIMAL
#define TOK_DECIMAL '.'
#endif
formatstr:
;Inputs:
; HL points to the null-terminated string of digits
; DE is the signed exponent.
;Outputs:
; The string has leading and trailing zeros stripped, a decimal is placed
; (if needed), and an exponent field is appended (if needed).
;Destroys:
; HL, DE, BC, AF
;Notes:
; This routine operates in-place. It assumes that there is enough space
; allocated for the string. At most MAX_FORMAT_LEN+10 bytes is needed,
; assuming the exponent can be up to 5 digits long.
;
; Skip over the negative sign, if any
ld a,(hl)
cp TOK_NEG
jr nz,$+3
inc hl
push de ; save the exponent
push hl
;Strip leading zeros
ld d,h
ld e,l
ld a,'0'
cp (hl) ;These two lines can be commented-out to save three
jr nz,formatstr_no_leading_zeros ;bytes at the expense of redundant processing.
formatstr_strip_leading_zeros:
cpi
jr z,formatstr_strip_leading_zeros
dec hl
; HL points to the first non-'0' digit
; DE points to the first digit
; Copy bytes from HL to DE until 0x00 is reached at HL or FORMAT_LEN digits are copied
#ifdef EXTERNAL_FORMAT_LEN
ld a,(EXTERNAL_FORMAT_LEN)
or a
jr nz,$+4
#endif
ld a,FORMAT_LEN
#ifdef EXTERNAL_FORMAT_LEN
cp MAX_FORMAT_LEN
jr c,$+4
ld a,MAX_FORMAT_LEN
#endif
ld c,a
xor a
ld b,a
formatstr_copy_digits:
cp (hl)
ldi
jp po,+_
jr nz,formatstr_copy_digits
_:
dec hl
ld (hl),0
formatstr_no_leading_zeros:
; there are no more leading zeros
; Truncate the number of digits if necessary based on FORMAT_LEN
call formatstr_remove_trailing_zeros
pop hl ; points to the first digit
pop de ; exponent
; Make sure the first digit isn't 0x00
ld a,(hl)
or a
jr nz,+_
ld (hl),'0'
inc hl
ld (hl),a
ret
_:
call formatstr_check_eng
jr c,formatstr_eng
inc de
bit 7,d
jr nz,formatstr_neg_exp
; Otherwise, we need to insert a decimal after DE digits (D is 0, though)
ld b,d
ld c,e
xor a
cp e
jr z,formatstr_insert_decimal
cpir
; If we have reached a 0x00, we may need to pad with zeros
jr z,formatstr_pad_right
; otherwise, let's insert the decimal
formatstr_insert_decimal:
ld a,(hl)
or a
ret z
ld a,TOK_DECIMAL
formatstr_insert_decimal_loop:
ld c,(hl) ; back up digit
ld (hl),a
inc hl
ld a,c
or a
jr nz,formatstr_insert_decimal_loop
ld (hl),a
ret
formatstr_neg_exp:
; Need to pad -DE 0s to the left
xor a
ld c,a
cpir
ld b,a
sub c
ld c,a
;HL-1 is where to start reading bytes
;HL-DE is where to start writing bytes
xor a
ld d,a
sub e ; A is the number of 0s to write
ld e,a
ex de,hl
add hl,de
ex de,hl
dec hl
; DE points to where to write the last byte
; HL points to where to read it from
; BC is the number of bytes to copy (it will be non-zero)
; A is the number of zeros to insert
lddr
;now from DE backwards, write A '0's
ex de,hl
ld b,a
ld (hl),'0'
dec hl
djnz $-3
; finally, write a '.'
ld (hl),TOK_DECIMAL
ret
formatstr_pad_right:
; append BC+1 0s
dec hl
inc bc
_:
ld (hl),'0'
cpi
jp pe,-_
ld (hl),0
ret
formatstr_eng:
; need to insert a decimal after the first digit
inc hl
call formatstr_insert_decimal
ld (hl),TOK_ENG
inc hl
bit 7,d
jr z,formatstr_exp_to_str
ld (hl),TOK_NEG
inc hl
xor a
sub e
ld e,a
sbc a,a
sub d
ld d,a
formatstr_exp_to_str:
ex de,hl
ld a,'0'-1
ld bc,-10000
_:
inc a
add hl,bc
jr c,-_
cp '0'
jr z,$+4
ld (de),a
inc de
ld a,'9'+1
ld bc,1000
_:
dec a
add hl,bc
jr nc,-_
cp '0'
jr z,$+4
ld (de),a
inc de
ld a,'0'-1
ld bc,-100
_:
inc a
add hl,bc
jr c,-_
cp '0'
jr z,$+4
ld (de),a
inc de
ld b,10
ld a,l
_:
add a,10
dec b
jr nc,-_
ex de,hl
jr z,formatstr_eng_last_digit
set 4,b
set 5,b
ld (hl),b
inc hl
formatstr_eng_last_digit:
add a,'0'
ld (hl),a
inc hl
ld (hl),0
ret
formatstr_remove_trailing_zeros:
; first, seek the end of the string
xor a
ld c,a
ld b,a
cpir
dec hl
ld a,'0'
_:
dec hl
cp (hl)
jr z,-_
inc hl
ld (hl),0
ret
formatstr_check_eng:
; Return carry flag set if engineering format is required, else nc
;
; If the exponent is greater than FORMAT_MAX_ENGINEERING, then use enginieering
; notation. Note that FORMAT_MAX_ENGINEERING < 256, so check that D = -1 or 0
ld a,d
inc a
jr z,formatstr_check_eng_neg
add a,254
ret c ;the exponent is too big in magnitude, engineering format is required.
; The exponent is positive and less than 256
#ifdef EXTERNAL_FORMAT_MAX_ENGINEERING
ld a,(EXTERNAL_FORMAT_MAX_ENGINEERING)
or a
jr nz,+_
#ifdef FORMAT_MAX_ENGINEERING
ld a,FORMAT_MAX_ENGINEERING
#else
#ifdef EXTERNAL_FORMAT_LEN
ld a,(EXTERNAL_FORMAT_LEN)
or a
jr nz,$+4
#endif
ld a,FORMAT_LEN
#endif
_:
#else
#ifdef FORMAT_MAX_ENGINEERING
ld a,FORMAT_MAX_ENGINEERING
#else
#ifdef EXTERNAL_FORMAT_LEN
ld a,(EXTERNAL_FORMAT_LEN)
or a
jr nz,$+4
#endif
ld a,FORMAT_LEN
#endif
#endif
cp e
ret
formatstr_check_eng_neg:
;The exponent is negative and greater than or equal to -256
#ifdef EXTERNAL_FORMAT_MIN_ENGINEERING
ld a,(EXTERNAL_FORMAT_MIN_ENGINEERING)
or a
jr nz,$+3
ld a,FORMAT_MIN_ENGINEERING
#else
ld a,FORMAT_MIN_ENGINEERING
#endif
cp e
ccf
ret
#endif