306 lines
6.5 KiB
NASM
306 lines
6.5 KiB
NASM
; *** Requirements ***
|
|
; lib/util
|
|
; *** Code ***
|
|
|
|
; Parse the hex char at A and extract it's 0-15 numerical value. Put the result
|
|
; in A.
|
|
;
|
|
; On success, the carry flag is reset. On error, it is set.
|
|
parseHex:
|
|
; First, let's see if we have an easy 0-9 case
|
|
|
|
add a, 0xc6 ; maps '0'-'9' onto 0xf6-0xff
|
|
sub 0xf6 ; maps to 0-9 and carries if not a digit
|
|
ret nc
|
|
|
|
and 0xdf ; converts lowercase to uppercase
|
|
add a, 0xe9 ; map 0x11-x017 onto 0xFA - 0xFF
|
|
sub 0xfa ; map onto 0-6
|
|
ret c
|
|
; we have an A-F digit
|
|
add a, 10 ; C is clear, map back to 0xA-0xF
|
|
ret
|
|
|
|
|
|
; Parses 2 characters of the string pointed to by HL and returns the numerical
|
|
; value in A. If the second character is a "special" character (<0x21) we don't
|
|
; error out: the result will be the one from the first char only.
|
|
; HL is set to point to the last char of the pair.
|
|
;
|
|
; On success, the carry flag is reset. On error, it is set.
|
|
parseHexPair:
|
|
push bc
|
|
|
|
ld a, (hl)
|
|
call parseHex
|
|
jr c, .end ; error? goto end, keeping the C flag on
|
|
rla \ rla \ rla \ rla ; let's push this in MSB
|
|
ld b, a
|
|
inc hl
|
|
ld a, (hl)
|
|
cp 0x21
|
|
jr c, .single ; special char? single digit
|
|
call parseHex
|
|
jr c, .end ; error?
|
|
or b ; join left-shifted + new. we're done!
|
|
; C flag was set on parseHex and is necessarily clear at this point
|
|
jr .end
|
|
|
|
.single:
|
|
; If we have a single digit, our result is already stored in B, but
|
|
; we have to right-shift it back.
|
|
ld a, b
|
|
and 0xf0
|
|
rra \ rra \ rra \ rra
|
|
dec hl
|
|
|
|
.end:
|
|
pop bc
|
|
ret
|
|
|
|
; Parse the decimal char at A and extract it's 0-9 numerical value. Put the
|
|
; result in A.
|
|
;
|
|
; On success, the carry flag is reset. On error, it is set.
|
|
; Also, zero flag set if '0'
|
|
; parseDecimalDigit has been replaced with the following code inline:
|
|
; add a, 0xff-'9' ; maps '0'-'9' onto 0xf6-0xff
|
|
; sub 0xff-9 ; maps to 0-9 and carries if not a digit
|
|
|
|
; Parse string at (HL) as a decimal value and return value in IX under the
|
|
; same conditions as parseLiteral.
|
|
; Sets Z on success, unset on error.
|
|
; To parse successfully, all characters following HL must be digits and those
|
|
; digits must form a number that fits in 16 bits. To end the number, both \0
|
|
; and whitespaces (0x20 and 0x09) are accepted. There must be at least one
|
|
; digit in the string.
|
|
|
|
parseDecimal:
|
|
push hl
|
|
|
|
ld a, (hl)
|
|
add a, 0xff-'9' ; maps '0'-'9' onto 0xf6-0xff
|
|
sub 0xff-9 ; maps to 0-9 and carries if not a digit
|
|
jr c, .error ; not a digit on first char? error
|
|
exx ; preserve bc, hl, de
|
|
ld h, 0
|
|
ld l, a ; load first digit in without multiplying
|
|
ld b, 3 ; Carries can only occur for decimals >=5 in length
|
|
|
|
.loop:
|
|
exx
|
|
inc hl
|
|
ld a, (hl)
|
|
exx
|
|
|
|
; inline parseDecimalDigit
|
|
add a, 0xff-'9' ; maps '0'-'9' onto 0xf6-0xff
|
|
sub 0xff-9 ; maps to 0-9 and carries if not a digit
|
|
jr c, .end
|
|
|
|
add hl, hl ; x2
|
|
ld d, h
|
|
ld e, l ; de is x2
|
|
add hl, hl ; x4
|
|
add hl, hl ; x8
|
|
add hl, de ; x10
|
|
ld d, 0
|
|
ld e, a
|
|
add hl, de
|
|
jr c, .end ; if hl was 0x1999, it may carry here
|
|
djnz .loop
|
|
|
|
|
|
inc b ; so loop only executes once more
|
|
; only numbers >0x1999 can carry when multiplied by 10.
|
|
ld de, 0xE666
|
|
ex de, hl
|
|
add hl, de
|
|
ex de, hl
|
|
jr nc, .loop ; if it doesn't carry, it's small enough
|
|
|
|
exx
|
|
inc hl
|
|
ld a, (hl)
|
|
exx
|
|
add a, 0xd0 ; the next line expects a null to be mapped to 0xd0
|
|
.end:
|
|
; Because of the add and sub in parseDecimalDigit, null is mapped
|
|
; to 0x00+(0xff-'9')-(0xff-9)=-0x30=0xd0
|
|
sub 0xd0 ; if a is null, set Z
|
|
; a is checked for null before any errors
|
|
push hl \ pop ix
|
|
exx ; restore original de and bc
|
|
pop hl
|
|
ret z
|
|
; A is not 0? Ok, but if it's a space, we're happy too.
|
|
jp isWS
|
|
.error:
|
|
pop hl
|
|
jp unsetZ
|
|
|
|
; Parse string at (HL) as a hexadecimal value and return value in IX under the
|
|
; same conditions as parseLiteral.
|
|
parseHexadecimal:
|
|
call hasHexPrefix
|
|
ret nz
|
|
push hl
|
|
push de
|
|
ld d, 0
|
|
inc hl ; get rid of "0x"
|
|
inc hl
|
|
call strlen
|
|
cp 3
|
|
jr c, .single
|
|
cp 4
|
|
jr c, .doubleShort ; 0x123
|
|
cp 5
|
|
jr c, .double ; 0x1234
|
|
; too long, error
|
|
jr .error
|
|
.double:
|
|
call parseHexPair
|
|
jr c, .error
|
|
inc hl ; now HL is on first char of next pair
|
|
ld d, a
|
|
jr .single
|
|
.doubleShort:
|
|
ld a, (hl)
|
|
call parseHex
|
|
jr c, .error
|
|
inc hl ; now HL is on first char of next pair
|
|
ld d, a
|
|
.single:
|
|
call parseHexPair
|
|
jr c, .error
|
|
ld e, a
|
|
cp a ; ensure Z
|
|
jr .end
|
|
.error:
|
|
call unsetZ
|
|
.end:
|
|
push de \ pop ix
|
|
pop de
|
|
pop hl
|
|
ret
|
|
|
|
; Sets Z if (HL) has a '0x' prefix.
|
|
hasHexPrefix:
|
|
ld a, (hl)
|
|
cp '0'
|
|
ret nz
|
|
push hl
|
|
inc hl
|
|
ld a, (hl)
|
|
cp 'x'
|
|
pop hl
|
|
ret
|
|
|
|
; Parse string at (HL) as a binary value (0b010101) and return value in IX.
|
|
; High IX byte is always clear.
|
|
; Sets Z on success.
|
|
parseBinaryLiteral:
|
|
call hasBinPrefix
|
|
ret nz
|
|
push bc
|
|
push hl
|
|
push de
|
|
ld d, 0
|
|
inc hl ; get rid of "0b"
|
|
inc hl
|
|
call strlen
|
|
or a
|
|
jr z, .error ; empty, error
|
|
cp 9
|
|
jr nc, .error ; >= 9, too long
|
|
; We have a string of 8 or less chars. What we'll do is that for each
|
|
; char, we rotate left and set the LSB according to whether we have '0'
|
|
; or '1'. Error out on anything else. C is our stored result.
|
|
ld b, a ; we loop for "strlen" times
|
|
ld c, 0 ; our stored result
|
|
.loop:
|
|
rlc c
|
|
ld a, (hl)
|
|
inc hl
|
|
cp '0'
|
|
jr z, .nobit ; no bit to set
|
|
cp '1'
|
|
jr nz, .error ; not 0 or 1
|
|
; We have a bit to set
|
|
inc c
|
|
.nobit:
|
|
djnz .loop
|
|
ld e, c
|
|
cp a ; ensure Z
|
|
jr .end
|
|
.error:
|
|
call unsetZ
|
|
.end:
|
|
push de \ pop ix
|
|
pop de
|
|
pop hl
|
|
pop bc
|
|
ret
|
|
|
|
; Sets Z if (HL) has a '0b' prefix.
|
|
hasBinPrefix:
|
|
ld a, (hl)
|
|
cp '0'
|
|
ret nz
|
|
push hl
|
|
inc hl
|
|
ld a, (hl)
|
|
cp 'b'
|
|
pop hl
|
|
ret
|
|
|
|
; Parse string at (HL) and, if it is a char literal, sets Z and return
|
|
; corresponding value in IX. High IX byte is always clear.
|
|
;
|
|
; A valid char literal starts with ', ends with ' and has one character in the
|
|
; middle. No escape sequence are accepted, but ''' will return the apostrophe
|
|
; character.
|
|
parseCharLiteral:
|
|
ld a, 0x27 ; apostrophe (') char
|
|
cp (hl)
|
|
ret nz
|
|
|
|
push hl
|
|
push de
|
|
inc hl
|
|
inc hl
|
|
cp (hl)
|
|
jr nz, .end ; not ending with an apostrophe
|
|
inc hl
|
|
ld a, (hl)
|
|
or a ; cp 0
|
|
jr nz, .end ; string has to end there
|
|
; Valid char, good
|
|
ld d, a ; A is zero, take advantage of that
|
|
dec hl
|
|
dec hl
|
|
ld a, (hl)
|
|
ld e, a
|
|
cp a ; ensure Z
|
|
.end:
|
|
push de \ pop ix
|
|
pop de
|
|
pop hl
|
|
ret
|
|
|
|
; Parses the string at (HL) and returns the 16-bit value in IX. The string
|
|
; can be a decimal literal (1234), a hexadecimal literal (0x1234) or a char
|
|
; literal ('X').
|
|
;
|
|
; As soon as the number doesn't fit 16-bit any more, parsing stops and the
|
|
; number is invalid. If the number is valid, Z is set, otherwise, unset.
|
|
parseLiteral:
|
|
call parseCharLiteral
|
|
ret z
|
|
call parseHexadecimal
|
|
ret z
|
|
call parseBinaryLiteral
|
|
ret z
|
|
jp parseDecimal
|
|
|