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https://github.com/hsoft/collapseos.git
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549cf74e9d
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.
570 lines
12 KiB
NASM
570 lines
12 KiB
NASM
; *** Collapse OS lib copy ***
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; In the process of Forth-ifying Collapse OS, apps will be slowly rewritten to
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; Forth and the concept of ASM libs will become obsolete. To facilitate this
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; transition, I make, right now, a copy of the routines actually used by Forth's
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; native core. This also has the effect of reducing binary size right now and
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; give us an idea of Forth's compactness.
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; These routines below are copy/paste from apps/lib.
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; make Z the opposite of what it is now
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toggleZ:
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jp z, unsetZ
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cp a
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ret
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; Copy string from (HL) in (DE), that is, copy bytes until a null char is
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; encountered. The null char is also copied.
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; HL and DE point to the char right after the null char.
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strcpyM:
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ld a, (hl)
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ld (de), a
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inc hl
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inc de
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or a
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jr nz, strcpyM
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ret
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; Like strcpyM, but preserve HL and DE
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strcpy:
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push hl
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push de
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call strcpyM
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pop de
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pop hl
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ret
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; Compares strings pointed to by HL and DE until one of them hits its null char.
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; If equal, Z is set. If not equal, Z is reset. C is set if HL > DE
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strcmp:
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push hl
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push de
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.loop:
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ld a, (de)
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cp (hl)
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jr nz, .end ; not equal? break early. NZ is carried out
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; to the caller
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or a ; If our chars are null, stop the cmp
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inc hl
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inc de
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jr nz, .loop ; Z is carried through
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.end:
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pop de
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pop hl
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; Because we don't call anything else than CP that modify the Z flag,
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; our Z value will be that of the last cp (reset if we broke the loop
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; early, set otherwise)
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ret
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; Given a string at (HL), move HL until it points to the end of that string.
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strskip:
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push bc
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ex af, af'
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xor a ; look for null char
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ld b, a
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ld c, a
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cpir ; advances HL regardless of comparison, so goes one too far
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dec hl
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ex af, af'
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pop bc
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ret
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; Borrowed from Tasty Basic by Dimitri Theulings (GPL).
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; Divide HL by DE, placing the result in BC and the remainder in HL.
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divide:
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push hl ; --> lvl 1
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ld l, h ; divide h by de
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ld h, 0
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call .dv1
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ld b, c ; save result in b
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ld a, l ; (remainder + l) / de
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pop hl ; <-- lvl 1
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ld h, a
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.dv1:
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ld c, 0xff ; result in c
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.dv2:
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inc c ; dumb routine
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call .subde ; divide using subtract and count
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jr nc, .dv2
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add hl, de
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ret
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.subde:
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ld a, l
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sub e ; subtract de from hl
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ld l, a
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ld a, h
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sbc a, d
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ld h, a
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ret
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; DE * BC -> DE (high) and HL (low)
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multDEBC:
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ld hl, 0
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ld a, 0x10
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.loop:
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add hl, hl
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rl e
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rl d
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jr nc, .noinc
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add hl, bc
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jr nc, .noinc
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inc de
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.noinc:
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dec a
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jr nz, .loop
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ret
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; Parse the hex char at A and extract it's 0-15 numerical value. Put the result
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; in A.
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;
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; On success, the carry flag is reset. On error, it is set.
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parseHex:
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; First, let's see if we have an easy 0-9 case
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add a, 0xc6 ; maps '0'-'9' onto 0xf6-0xff
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sub 0xf6 ; maps to 0-9 and carries if not a digit
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ret nc
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and 0xdf ; converts lowercase to uppercase
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add a, 0xe9 ; map 0x11-x017 onto 0xFA - 0xFF
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sub 0xfa ; map onto 0-6
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ret c
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; we have an A-F digit
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add a, 10 ; C is clear, map back to 0xA-0xF
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ret
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; Parse string at (HL) as a decimal value and return value in DE.
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; Reads as many digits as it can and stop when:
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; 1 - A non-digit character is read
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; 2 - The number overflows from 16-bit
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; HL is advanced to the character following the last successfully read char.
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; Error conditions are:
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; 1 - There wasn't at least one character that could be read.
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; 2 - Overflow.
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; Sets Z on success, unset on error.
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parseDecimal:
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; First char is special: it has to succeed.
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ld a, (hl)
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; Parse the decimal char at A and extract it's 0-9 numerical value. Put the
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; result in A.
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; On success, the carry flag is reset. On error, it is set.
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add a, 0xff-'9' ; maps '0'-'9' onto 0xf6-0xff
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sub 0xff-9 ; maps to 0-9 and carries if not a digit
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ret c ; Error. If it's C, it's also going to be NZ
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; During this routine, we switch between HL and its shadow. On one side,
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; we have HL the string pointer, and on the other side, we have HL the
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; numerical result. We also use EXX to preserve BC, saving us a push.
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parseDecimalSkip: ; enter here to skip parsing the first digit
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exx ; HL as a result
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ld h, 0
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ld l, a ; load first digit in without multiplying
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.loop:
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exx ; HL as a string pointer
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inc hl
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ld a, (hl)
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exx ; HL as a numerical result
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; same as other above
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add a, 0xff-'9'
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sub 0xff-9
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jr c, .end
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ld b, a ; we can now use a for overflow checking
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add hl, hl ; x2
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sbc a, a ; a=0 if no overflow, a=0xFF otherwise
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ld d, h
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ld e, l ; de is x2
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add hl, hl ; x4
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rla
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add hl, hl ; x8
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rla
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add hl, de ; x10
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rla
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ld d, a ; a is zero unless there's an overflow
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ld e, b
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add hl, de
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adc a, a ; same as rla except affects Z
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; Did we oveflow?
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jr z, .loop ; No? continue
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; error, NZ already set
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exx ; HL is now string pointer, restore BC
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; HL points to the char following the last success.
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ret
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.end:
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push hl ; --> lvl 1, result
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exx ; HL as a string pointer, restore BC
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pop de ; <-- lvl 1, result
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cp a ; ensure Z
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ret
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; Parse string at (HL) as a hexadecimal value without the "0x" prefix and
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; return value in DE.
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; HL is advanced to the character following the last successfully read char.
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; Sets Z on success.
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parseHexadecimal:
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ld a, (hl)
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call parseHex ; before "ret c" is "sub 0xfa" in parseHex
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; so carry implies not zero
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ret c ; we need at least one char
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push bc
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ld de, 0
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ld b, d
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ld c, d
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; The idea here is that the 4 hex digits of the result can be represented "bdce",
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; where each register holds a single digit. Then the result is simply
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; e = (c << 4) | e, d = (b << 4) | d
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; However, the actual string may be of any length, so when loading in the most
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; significant digit, we don't know which digit of the result it actually represents
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; To solve this, after a digit is loaded into a (and is checked for validity),
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; all digits are moved along, with e taking the latest digit.
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.loop:
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dec b
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inc b ; b should be 0, else we've overflowed
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jr nz, .end ; Z already unset if overflow
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ld b, d
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ld d, c
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ld c, e
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ld e, a
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inc hl
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ld a, (hl)
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call parseHex
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jr nc, .loop
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ld a, b
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add a, a \ add a, a \ add a, a \ add a, a
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or d
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ld d, a
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ld a, c
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add a, a \ add a, a \ add a, a \ add a, a
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or e
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ld e, a
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xor a ; ensure z
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.end:
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pop bc
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ret
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; Parse string at (HL) as a binary value (010101) without the "0b" prefix and
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; return value in E. D is always zero.
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; HL is advanced to the character following the last successfully read char.
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; Sets Z on success.
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parseBinaryLiteral:
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ld de, 0
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.loop:
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ld a, (hl)
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add a, 0xff-'1'
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sub 0xff-1
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jr c, .end
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rlc e ; sets carry if overflow, and affects Z
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ret c ; Z unset if carry set, since bit 0 of e must be set
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add a, e
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ld e, a
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inc hl
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jr .loop
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.end:
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; HL is properly set
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xor a ; ensure Z
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ret
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; Parses the string at (HL) and returns the 16-bit value in DE. The string
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; can be a decimal literal (1234), a hexadecimal literal (0x1234) or a char
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; literal ('X').
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; HL is advanced to the character following the last successfully read char.
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;
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; As soon as the number doesn't fit 16-bit any more, parsing stops and the
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; number is invalid. If the number is valid, Z is set, otherwise, unset.
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parseLiteral:
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ld de, 0 ; pre-fill
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ld a, (hl)
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cp 0x27 ; apostrophe
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jr z, .char
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; inline parseDecimalDigit
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add a, 0xc6 ; maps '0'-'9' onto 0xf6-0xff
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sub 0xf6 ; maps to 0-9 and carries if not a digit
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ret c
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; a already parsed so skip first few instructions of parseDecimal
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jp nz, parseDecimalSkip
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; maybe hex, maybe binary
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inc hl
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ld a, (hl)
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inc hl ; already place it for hex or bin
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cp 'x'
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jr z, parseHexadecimal
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cp 'b'
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jr z, parseBinaryLiteral
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; nope, just a regular decimal
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dec hl \ dec hl
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jp parseDecimal
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; Parse string at (HL) and, if it is a char literal, sets Z and return
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; corresponding value in E. D is always zero.
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; HL is advanced to the character following the last successfully read char.
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;
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; A valid char literal starts with ', ends with ' and has one character in the
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; middle. No escape sequence are accepted, but ''' will return the apostrophe
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; character.
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.char:
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inc hl
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ld e, (hl) ; our result
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inc hl
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cp (hl)
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; advance HL and return if good char
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inc hl
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ret z
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; Z unset and there's an error
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; In all error conditions, HL is advanced by 3. Rewind.
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dec hl \ dec hl \ dec hl
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; NZ already set
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ret
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; *** Forth-specific part ***
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; Return address of scratchpad in HL
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pad:
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ld hl, (HERE)
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ld a, PADDING
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jp addHL
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; Advance (INPUTPOS) until a non-whitespace is met. If needed,
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; call fetchline.
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; Set HL to newly set (INPUTPOS)
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toword:
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ld hl, (INPUTPOS)
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; skip leading whitespace
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dec hl ; offset leading "inc hl"
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.loop:
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inc hl
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ld a, (hl)
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or a
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; When at EOL, fetch a new line directly
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jr z, .empty
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cp ' '+1
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jr c, .loop
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ret
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.empty:
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call fetchline
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jr toword
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; Read word from (INPUTPOS) and return, in HL, a null-terminated word.
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; Advance (INPUTPOS) to the character following the whitespace ending the
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; word.
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; When we're at EOL, we call fetchline directly, so this call always returns
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; a word.
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readword:
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call toword
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push hl ; --> lvl 1. that's our result
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.loop:
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inc hl
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ld a, (hl)
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; special case: is A null? If yes, we will *not* inc A so that we don't
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; go over the bounds of our input string.
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or a
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jr z, .noinc
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cp ' '+1
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jr nc, .loop
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; we've just read a whitespace, HL is pointing to it. Let's transform
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; it into a null-termination, inc HL, then set (INPUTPOS).
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xor a
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ld (hl), a
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inc hl
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.noinc:
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ld (INPUTPOS), hl
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pop hl ; <-- lvl 1. our result
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ret ; Z set from XOR A
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; Sets Z if (HL) == E and (HL+1) == D
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HLPointsDE:
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ld a, (hl)
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cp e
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ret nz ; no
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inc hl
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ld a, (hl)
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dec hl
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cp d ; Z has our answer
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ret
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HLPointsNUMBER:
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push de
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ld de, NUMBER
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call HLPointsDE
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pop de
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ret
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HLPointsLIT:
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push de
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ld de, LIT
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call HLPointsDE
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pop de
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ret
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HLPointsBR:
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push de
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ld de, FBR
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call HLPointsDE
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jr z, .end
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ld de, BBR
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call HLPointsDE
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.end:
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pop de
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ret
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; Skip the compword where HL is currently pointing. If it's a regular word,
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; it's easy: we inc by 2. If it's a NUMBER, we inc by 4. If it's a LIT, we skip
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; to after null-termination.
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compSkip:
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call HLPointsNUMBER
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jr z, .isNum
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call HLPointsBR
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jr z, .isBranch
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call HLPointsLIT
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jr nz, .isWord
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; We have a literal
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inc hl \ inc hl
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call strskip
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inc hl ; byte after word termination
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ret
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.isNum:
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; skip by 4
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inc hl
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; continue to isBranch
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.isBranch:
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; skip by 3
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inc hl
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; continue to isWord
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.isWord:
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; skip by 2
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inc hl \ inc hl
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ret
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; Find the entry corresponding to word where (HL) points to and sets DE to
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; point to that entry.
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; Z if found, NZ if not.
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find:
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push hl
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push bc
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ld de, (CURRENT)
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ld bc, CODELINK_OFFSET
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.inner:
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; DE is a wordref, let's go to beginning of struct
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push de ; --> lvl 1
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or a ; clear carry
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ex de, hl
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sbc hl, bc
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ex de, hl ; We're good, DE points to word name
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ld a, NAMELEN
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call strncmp
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pop de ; <-- lvl 1, return to wordref
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jr z, .end ; found
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call .prev
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jr nz, .inner
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; Z set? end of dict unset Z
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inc a
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.end:
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pop bc
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pop hl
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ret
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; For DE being a wordref, move DE to the previous wordref.
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; Z is set if DE point to 0 (no entry). NZ if not.
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.prev:
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dec de \ dec de \ dec de ; prev field
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call intoDE
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; DE points to prev. Is it zero?
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xor a
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or d
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or e
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; Z will be set if DE is zero
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ret
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; Write compiled data from HL into IY, advancing IY at the same time.
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wrCompHL:
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ld (iy), l
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inc iy
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ld (iy), h
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inc iy
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ret
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; Spit name + prev in (HERE) and adjust (HERE) and (CURRENT)
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; HL points to new (HERE)
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entryhead:
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call readword
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ld de, (HERE)
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call strcpy
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ex de, hl ; (HERE) now in HL
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ld de, (CURRENT)
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ld a, NAMELEN
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call addHL
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call DEinHL
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; Set word flags: not IMMED, not UNWORD, so it's 0
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xor a
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ld (hl), a
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inc hl
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ld (CURRENT), hl
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ld (HERE), hl
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ret
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; Sets Z if wordref at HL is of the IMMEDIATE type
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HLisIMMED:
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dec hl
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bit FLAG_IMMED, (hl)
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inc hl
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; We need an invert flag. We want to Z to be set when flag is non-zero.
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jp toggleZ
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; Sets Z if wordref at (HL) is of the IMMEDIATE type
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HLPointsIMMED:
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push hl
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call intoHL
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call HLisIMMED
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pop hl
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ret
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; Sets Z if wordref at HL is of the UNWORD type
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HLisUNWORD:
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dec hl
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bit FLAG_UNWORD, (hl)
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inc hl
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; We need an invert flag. We want to Z to be set when flag is non-zero.
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jp toggleZ
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; Sets Z if wordref at (HL) is of the IMMEDIATE type
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HLPointsUNWORD:
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push hl
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call intoHL
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call HLisUNWORD
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pop hl
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ret
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; Checks flags Z and S and sets BC to 0 if Z, 1 if C and -1 otherwise
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flagsToBC:
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ld bc, 0
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ret z ; equal
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inc bc
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ret m ; >
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; <
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dec bc
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dec bc
|
|
ret
|
|
|
|
; Write DE in (HL), advancing HL by 2.
|
|
DEinHL:
|
|
ld (hl), e
|
|
inc hl
|
|
ld (hl), d
|
|
inc hl
|
|
ret
|
|
|
|
fetchline:
|
|
call printcrlf
|
|
call stdioReadLine
|
|
ld (INPUTPOS), hl
|
|
ret
|