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forth: inline code from "apps/lib"

Forth-ification of Collapse OS goes forward. What will happen is that assembly
code in apps/ will become Forth code. The concept of an assembler code library
will become obsolete.

However, Forth's core use some of that code. To facilitate the transition, I'm
inlining that code directly in Forth's code.
This commit is contained in:
Virgil Dupras 2020-03-17 12:49:06 -04:00
parent 017a469d9c
commit 549cf74e9d
4 changed files with 328 additions and 9 deletions

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@ -2,9 +2,6 @@
jp forthMain
.inc "core.asm"
.inc "lib/util.asm"
.inc "lib/parse.asm"
.inc "lib/ari.asm"
.equ FORTH_RAMSTART RAMSTART
.inc "forth/main.asm"
.inc "forth/util.asm"

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@ -1,3 +1,331 @@
; *** Collapse OS lib copy ***
; In the process of Forth-ifying Collapse OS, apps will be slowly rewritten to
; Forth and the concept of ASM libs will become obsolete. To facilitate this
; transition, I make, right now, a copy of the routines actually used by Forth's
; native core. This also has the effect of reducing binary size right now and
; give us an idea of Forth's compactness.
; These routines below are copy/paste from apps/lib.
; make Z the opposite of what it is now
toggleZ:
jp z, unsetZ
cp a
ret
; Copy string from (HL) in (DE), that is, copy bytes until a null char is
; encountered. The null char is also copied.
; HL and DE point to the char right after the null char.
strcpyM:
ld a, (hl)
ld (de), a
inc hl
inc de
or a
jr nz, strcpyM
ret
; Like strcpyM, but preserve HL and DE
strcpy:
push hl
push de
call strcpyM
pop de
pop hl
ret
; Compares strings pointed to by HL and DE until one of them hits its null char.
; If equal, Z is set. If not equal, Z is reset. C is set if HL > DE
strcmp:
push hl
push de
.loop:
ld a, (de)
cp (hl)
jr nz, .end ; not equal? break early. NZ is carried out
; to the caller
or a ; If our chars are null, stop the cmp
inc hl
inc de
jr nz, .loop ; Z is carried through
.end:
pop de
pop hl
; Because we don't call anything else than CP that modify the Z flag,
; our Z value will be that of the last cp (reset if we broke the loop
; early, set otherwise)
ret
; Given a string at (HL), move HL until it points to the end of that string.
strskip:
push bc
ex af, af'
xor a ; look for null char
ld b, a
ld c, a
cpir ; advances HL regardless of comparison, so goes one too far
dec hl
ex af, af'
pop bc
ret
; Borrowed from Tasty Basic by Dimitri Theulings (GPL).
; Divide HL by DE, placing the result in BC and the remainder in HL.
divide:
push hl ; --> lvl 1
ld l, h ; divide h by de
ld h, 0
call .dv1
ld b, c ; save result in b
ld a, l ; (remainder + l) / de
pop hl ; <-- lvl 1
ld h, a
.dv1:
ld c, 0xff ; result in c
.dv2:
inc c ; dumb routine
call .subde ; divide using subtract and count
jr nc, .dv2
add hl, de
ret
.subde:
ld a, l
sub e ; subtract de from hl
ld l, a
ld a, h
sbc a, d
ld h, a
ret
; DE * BC -> DE (high) and HL (low)
multDEBC:
ld hl, 0
ld a, 0x10
.loop:
add hl, hl
rl e
rl d
jr nc, .noinc
add hl, bc
jr nc, .noinc
inc de
.noinc:
dec a
jr nz, .loop
ret
; 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
; Parse string at (HL) as a decimal value and return value in DE.
; Reads as many digits as it can and stop when:
; 1 - A non-digit character is read
; 2 - The number overflows from 16-bit
; HL is advanced to the character following the last successfully read char.
; Error conditions are:
; 1 - There wasn't at least one character that could be read.
; 2 - Overflow.
; Sets Z on success, unset on error.
parseDecimal:
; First char is special: it has to succeed.
ld a, (hl)
; 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.
add a, 0xff-'9' ; maps '0'-'9' onto 0xf6-0xff
sub 0xff-9 ; maps to 0-9 and carries if not a digit
ret c ; Error. If it's C, it's also going to be NZ
; During this routine, we switch between HL and its shadow. On one side,
; we have HL the string pointer, and on the other side, we have HL the
; numerical result. We also use EXX to preserve BC, saving us a push.
parseDecimalSkip: ; enter here to skip parsing the first digit
exx ; HL as a result
ld h, 0
ld l, a ; load first digit in without multiplying
.loop:
exx ; HL as a string pointer
inc hl
ld a, (hl)
exx ; HL as a numerical result
; same as other above
add a, 0xff-'9'
sub 0xff-9
jr c, .end
ld b, a ; we can now use a for overflow checking
add hl, hl ; x2
sbc a, a ; a=0 if no overflow, a=0xFF otherwise
ld d, h
ld e, l ; de is x2
add hl, hl ; x4
rla
add hl, hl ; x8
rla
add hl, de ; x10
rla
ld d, a ; a is zero unless there's an overflow
ld e, b
add hl, de
adc a, a ; same as rla except affects Z
; Did we oveflow?
jr z, .loop ; No? continue
; error, NZ already set
exx ; HL is now string pointer, restore BC
; HL points to the char following the last success.
ret
.end:
push hl ; --> lvl 1, result
exx ; HL as a string pointer, restore BC
pop de ; <-- lvl 1, result
cp a ; ensure Z
ret
; Parse string at (HL) as a hexadecimal value without the "0x" prefix and
; return value in DE.
; HL is advanced to the character following the last successfully read char.
; Sets Z on success.
parseHexadecimal:
ld a, (hl)
call parseHex ; before "ret c" is "sub 0xfa" in parseHex
; so carry implies not zero
ret c ; we need at least one char
push bc
ld de, 0
ld b, d
ld c, d
; The idea here is that the 4 hex digits of the result can be represented "bdce",
; where each register holds a single digit. Then the result is simply
; e = (c << 4) | e, d = (b << 4) | d
; However, the actual string may be of any length, so when loading in the most
; significant digit, we don't know which digit of the result it actually represents
; To solve this, after a digit is loaded into a (and is checked for validity),
; all digits are moved along, with e taking the latest digit.
.loop:
dec b
inc b ; b should be 0, else we've overflowed
jr nz, .end ; Z already unset if overflow
ld b, d
ld d, c
ld c, e
ld e, a
inc hl
ld a, (hl)
call parseHex
jr nc, .loop
ld a, b
add a, a \ add a, a \ add a, a \ add a, a
or d
ld d, a
ld a, c
add a, a \ add a, a \ add a, a \ add a, a
or e
ld e, a
xor a ; ensure z
.end:
pop bc
ret
; Parse string at (HL) as a binary value (010101) without the "0b" prefix and
; return value in E. D is always zero.
; HL is advanced to the character following the last successfully read char.
; Sets Z on success.
parseBinaryLiteral:
ld de, 0
.loop:
ld a, (hl)
add a, 0xff-'1'
sub 0xff-1
jr c, .end
rlc e ; sets carry if overflow, and affects Z
ret c ; Z unset if carry set, since bit 0 of e must be set
add a, e
ld e, a
inc hl
jr .loop
.end:
; HL is properly set
xor a ; ensure Z
ret
; Parses the string at (HL) and returns the 16-bit value in DE. The string
; can be a decimal literal (1234), a hexadecimal literal (0x1234) or a char
; literal ('X').
; HL is advanced to the character following the last successfully read char.
;
; 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:
ld de, 0 ; pre-fill
ld a, (hl)
cp 0x27 ; apostrophe
jr z, .char
; inline parseDecimalDigit
add a, 0xc6 ; maps '0'-'9' onto 0xf6-0xff
sub 0xf6 ; maps to 0-9 and carries if not a digit
ret c
; a already parsed so skip first few instructions of parseDecimal
jp nz, parseDecimalSkip
; maybe hex, maybe binary
inc hl
ld a, (hl)
inc hl ; already place it for hex or bin
cp 'x'
jr z, parseHexadecimal
cp 'b'
jr z, parseBinaryLiteral
; nope, just a regular decimal
dec hl \ dec hl
jp parseDecimal
; Parse string at (HL) and, if it is a char literal, sets Z and return
; corresponding value in E. D is always zero.
; HL is advanced to the character following the last successfully read char.
;
; 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.
.char:
inc hl
ld e, (hl) ; our result
inc hl
cp (hl)
; advance HL and return if good char
inc hl
ret z
; Z unset and there's an error
; In all error conditions, HL is advanced by 3. Rewind.
dec hl \ dec hl \ dec hl
; NZ already set
ret
; *** Forth-specific part ***
; Return address of scratchpad in HL
pad:
ld hl, (HERE)

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@ -23,9 +23,6 @@
.equ STDIO_PUTC emulPutC
.inc "stdio.asm"
.inc "lib/util.asm"
.inc "lib/parse.asm"
.inc "lib/ari.asm"
.equ FORTH_RAMSTART STDIO_RAMEND
.inc "forth/main.asm"
.inc "forth/util.asm"

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@ -14,9 +14,6 @@
.equ STDIO_PUTC emulPutC
.inc "stdio.asm"
.inc "lib/util.asm"
.inc "lib/parse.asm"
.inc "lib/ari.asm"
.equ FORTH_RAMSTART STDIO_RAMEND
.inc "forth/main.asm"
.inc "forth/util.asm"