1
0
mirror of https://github.com/hsoft/collapseos.git synced 2024-12-25 04:48:06 +11:00

avra: refactor args parsing

This costs us a bit of space for now but should make things a lot
simpler down the road, especially with "alias ops" which are simple
syntactic sugar for another op.
This commit is contained in:
Virgil Dupras 2019-12-14 15:17:55 -05:00
parent fa75f30ffb
commit ab578159b7
3 changed files with 185 additions and 81 deletions

View File

@ -244,8 +244,9 @@ parseInstruction:
cp I_ASR
jr c, .spitNoArg
; spitRd5
call .readR5
ret nz
ld ix, argSpecs ; 'R', 0
call _parseArgs
ld a, h
call .placeRd
; continue to .spitNoArg
.spitNoArg:
@ -253,19 +254,18 @@ parseInstruction:
jp .spit
.spitRd5Rr5:
call .readR5
ld ix, argSpecs+2 ; 'R', 'R'
call _parseArgs
ret nz
ld a, h
call .placeRd
call readComma
call .readR5
ret nz
push af ; --> lvl 1
ld a, l
; let's start with the 4 lower bits
and 0xf
or c
; We now have our LSB in A. Let's spit it now.
call ioPutB
pop af ; <-- lvl 1
ld a, l
; and now that last high bit, currently bit 4, which must become bit 1
and 0b00010000
rra \ rra \ rra
@ -276,23 +276,18 @@ parseInstruction:
jr .spitMSB
.spitRdK8:
call .readR4
ld ix, argSpecs+6 ; 'r', 8
call _parseArgs
ret nz
ld a, h ; Rd
call .placeRd
call readComma
call readWord
call parseExpr
ret nz
ld a, 0xff
call .IX2A
ret nz
push af ; --> lvl 1
ld a, l ; K
; let's start with the 4 lower bits
and 0xf
or c
; We now have our LSB in A. Let's spit it now.
call ioPutB
pop af ; <-- lvl 1
ld a, l
; and now those high 4 bits
and 0xf0
rra \ rra \ rra \ rra
@ -301,13 +296,12 @@ parseInstruction:
jr .spitMSB
.spitRdBit:
call .readR5
ld ix, argSpecs+8 ; 'R', 'b'
call _parseArgs
ret nz
ld a, h
call .placeRd
call readComma
ret nz
call .readBit
ret nz
or l
; LSB is in A and is ready to go
call ioPutB
call .getUp1
@ -321,7 +315,7 @@ parseInstruction:
call parseExpr
ret nz
push ix \ pop hl
; We're doing the same dance as in .BR. See comments there.
; We're doing the same dance as in _readk7. See comments there.
ld de, 0xfff
add hl, de
jp c, unsetZ ; Carry? number is way too high.
@ -375,39 +369,24 @@ parseInstruction:
inc b
.skip1:
and 0b111
ld c, a
ld c, a ; can't store in H now, (HL) is used
ld ix, argSpecs+4 ; 7, 0
call _parseArgs
ret nz
; ok, now we can
ld l, h ; k in L
ld h, c ; bit in H
.spitBR2:
call readWord
ret nz
call parseExpr
ret nz
; IX contains an absolute value. Turn this into a -64/+63 relative
; value by subtracting PC from it. However, before we do that, let's
; add 0x7f to it, which we'll remove later. This will simplify bounds
; checks. (we use 7f instead of 3f because we deal in bytes here, not
; in words)
push ix \ pop hl
ld de, 0x7f
add hl, de ; Carry cleared
ex de, hl
call zasmGetPC ; --> HL
; The relative value is actually not relative to current PC, but to
; PC after the execution of this branching op. Increase HL by 2.
inc hl \ inc hl
ex de, hl
sbc hl, de
jp c, unsetZ ; Carry? error
ld de, 0x7f
sbc hl, de
; We're within bounds! However, our value in L is the number of
; relative *bytes*. The value we put there is the number of words.
; Thefore, relevant bits are 7:1
; bit in H, k in L.
; Our value in L is the number of relative *bytes*. The value we put
; there is the number of words. Therefore, relevant bits are 7:1
ld a, l
sla a \ rl b
sla a \ rl b
and 0b11111000
; k is now shifted by 3, two of those bits being in B. Let's OR A and
; C and we have our LSB ready to go.
or c
; H and we have our LSB ready to go.
or h
call ioPutB
; Good! MSB now. B is already good to go.
ld a, b
@ -417,10 +396,10 @@ parseInstruction:
; upcode becomes 0b111101
inc b
.rdBRBS:
call .readBit
ret nz
call readComma
ld ix, argSpecs+10 ; bit + k(7)
call _parseArgs
ret nz
; bit in H, k in L.
jr .spitBR2
; local routines
@ -447,8 +426,141 @@ parseInstruction:
ld hl, instrUpMasks2
jp addHL
.readR4:
call .readR5
; Argspecs: two bytes describing the arguments that are accepted. Possible
; values:
;
; 0 - None
; 7 - a k(7) address, relative to PC, *in bytes* (divide by 2 before writing)
; 8 - a K(8) value
; 'a' - A 5-bit I/O port value
; 'A' - A 6-bit I/O port value
; 'b' - a 0-7 bit value
; 'R' - an r5 value: r0-r31
; 'r' - an r4 value: r16-r31
;
; All arguments accept expressions, even 'r' ones: in 'r' args, we start by
; looking if the arg starts with 'r' or 'R'. If yes, it's a simple 'rXX' value,
; if not, we try parsing it as an expression and validate that it falls in the
; correct 0-31 or 16-31 range
argSpecs:
.db 'R', 0 ; Rd(5)
.db 'R', 'R' ; Rd(5) + Rr(5)
.db 7, 0 ; k(7)
.db 'r', 8 ; Rd(4) + K(8)
.db 'R', 'b' ; Rd(5) + bit
.db 'b', 7 ; bit + k(7)
; Parse arguments in (HL) according to specs in IX
; Puts the results in HL (which is not needed anymore after the parsing).
; First arg in H, second in L.
; This routine is not used in all cases, some ops don't fit this pattern well
; and thus parse their args themselves.
; Z for success.
_parseArgs:
; For the duration of the routine, our final value will be in DE, and
; then placed in HL at the end.
push de
call readWord
jr nz, .end
ld a, (ix)
call .parse
jr nz, .end
ld d, a
ld a, (ix+1)
or a
jr z, .end ; no arg
call readComma
jr nz, .end
call readWord
jr nz, .end
ld a, (ix+1)
call .parse
jr nz, .end
; we're done with (HL) now
ld l, a
cp a ; ensure Z
.end:
ld h, d
pop de
ret
; Parse a single arg specified in A and returns its value in A
; Z for success
.parse:
cp 'R'
jr z, _readR5
cp 'r'
jr z, _readR4
cp 'b'
jr z, _readBit
cp 7
jr z, _readk7
cp 8
jr z, _readK8
ret ; something's wrong
_readBit:
push ix
call parseExpr
ld a, 7
call _IX2A
jr nz, .end
or c
ld c, a
cp a ; ensure Z
.end:
pop ix
ret
_readk7:
push hl
push de
push ix
call parseExpr
jr nz, .end
; IX contains an absolute value. Turn this into a -64/+63 relative
; value by subtracting PC from it. However, before we do that, let's
; add 0x7f to it, which we'll remove later. This will simplify bounds
; checks. (we use 7f instead of 3f because we deal in bytes here, not
; in words)
push ix \ pop hl
ld de, 0x7f
add hl, de ; Carry cleared
ex de, hl
call zasmGetPC ; --> HL
; The relative value is actually not relative to current PC, but to
; PC after the execution of this branching op. Increase HL by 2.
inc hl \ inc hl
ex de, hl
sbc hl, de
jp c, .err ; Carry? error
ld de, 0x7f
sbc hl, de
; We're within bounds! However, our value in L is the number of
; relative *bytes*.
ld a, l
cp a ; ensure Z
.end:
pop ix
pop de
pop hl
ret
.err:
call unsetZ
jr .end
_readK8:
push ix
call parseExpr
jr nz, .end
ld a, 0xff
call _IX2A
.end:
pop ix
ret
_readR4:
call _readR5
ret nz
; has to be in the 16-31 range
sub 0x10
@ -458,34 +570,25 @@ parseInstruction:
; read a rXX argument and return register number in A.
; Set Z for success.
.readR5:
call readWord
_readR5:
push ix
ld a, (hl)
call upcase
cp 'R'
ret nz ; not a register
jr nz, .end ; not a register
inc hl
call parseDecimal
ret nz
jr nz, .end
ld a, 31
jr .IX2A
.readBit:
call readWord
ret nz
call parseExpr
ld a, 7
call .IX2A
ret nz
or c
ld c, a
cp a ; ensure Z
call _IX2A
.end:
pop ix
ret
; Put IX's LSB into A and, additionally, ensure that the new value is <=
; than what was previously in A.
; Z for success.
.IX2A:
_IX2A:
push ix \ pop hl
cp l
jp c, unsetZ ; A < L
@ -495,3 +598,5 @@ parseInstruction:
ld a, l
; Z set from "or a"
ret

View File

@ -80,8 +80,10 @@ ioGetB:
call ioInInclude
jr z, .normalmode
; We're in "include mode", read from FS
push ix ; --> lvl 1
ld ix, IO_INCLUDE_BLK
call _blkGetB
pop ix ; <-- lvl 1
jr nz, .includeEOF
cp 0x0a ; newline
ret nz ; not newline? nothing to do
@ -111,9 +113,11 @@ ioGetB:
; continue on to "normal" reading. We don't want to return our zero
.normalmode:
; normal mode, read from IN stream
push ix ; --> lvl 1
ld ix, IO_IN_BLK
call _blkGetB
cp 0x0a ; newline
pop ix ; <-- lvl 1
cp LF ; newline
ret nz ; not newline? return
; inc current lineno
push hl
@ -130,10 +134,6 @@ ioGetB:
pop af
ret
_callIX:
jp (ix)
ret
; Put back non-zero character A into the "ioGetB stack". The next ioGetB call,
; instead of reading from IO_IN_BLK, will return that character. That's the
; easiest way I found to handle the readWord/gotoNextLine problem.

View File

@ -155,8 +155,7 @@ readComma:
cp ','
ret z
call ioPutBack
call unsetZ
ret
jp unsetZ
; Read ioGetB until we reach the beginning of next line, skipping comments if
; necessary. This skips all whitespace, \n, \r, comments until we reach the