mirror of https://github.com/hsoft/collapseos.git
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
parent
fa75f30ffb
commit
ab578159b7
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@ -244,8 +244,9 @@ parseInstruction:
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cp I_ASR
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jr c, .spitNoArg
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; spitRd5
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call .readR5
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ret nz
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ld ix, argSpecs ; 'R', 0
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call _parseArgs
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ld a, h
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call .placeRd
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; continue to .spitNoArg
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.spitNoArg:
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@ -253,19 +254,18 @@ parseInstruction:
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jp .spit
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.spitRd5Rr5:
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call .readR5
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ld ix, argSpecs+2 ; 'R', 'R'
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call _parseArgs
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ret nz
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ld a, h
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call .placeRd
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call readComma
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call .readR5
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ret nz
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push af ; --> lvl 1
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ld a, l
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; let's start with the 4 lower bits
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and 0xf
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or c
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; We now have our LSB in A. Let's spit it now.
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call ioPutB
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pop af ; <-- lvl 1
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ld a, l
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; and now that last high bit, currently bit 4, which must become bit 1
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and 0b00010000
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rra \ rra \ rra
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@ -276,23 +276,18 @@ parseInstruction:
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jr .spitMSB
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.spitRdK8:
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call .readR4
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ld ix, argSpecs+6 ; 'r', 8
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call _parseArgs
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ret nz
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ld a, h ; Rd
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call .placeRd
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call readComma
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call readWord
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call parseExpr
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ret nz
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ld a, 0xff
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call .IX2A
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ret nz
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push af ; --> lvl 1
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ld a, l ; K
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; let's start with the 4 lower bits
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and 0xf
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or c
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; We now have our LSB in A. Let's spit it now.
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call ioPutB
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pop af ; <-- lvl 1
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ld a, l
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; and now those high 4 bits
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and 0xf0
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rra \ rra \ rra \ rra
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@ -301,13 +296,12 @@ parseInstruction:
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jr .spitMSB
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.spitRdBit:
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call .readR5
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ld ix, argSpecs+8 ; 'R', 'b'
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call _parseArgs
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ret nz
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ld a, h
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call .placeRd
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call readComma
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ret nz
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call .readBit
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ret nz
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or l
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; LSB is in A and is ready to go
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call ioPutB
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call .getUp1
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@ -321,7 +315,7 @@ parseInstruction:
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call parseExpr
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ret nz
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push ix \ pop hl
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; We're doing the same dance as in .BR. See comments there.
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; We're doing the same dance as in _readk7. See comments there.
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ld de, 0xfff
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add hl, de
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jp c, unsetZ ; Carry? number is way too high.
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@ -375,39 +369,24 @@ parseInstruction:
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inc b
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.skip1:
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and 0b111
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ld c, a
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ld c, a ; can't store in H now, (HL) is used
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ld ix, argSpecs+4 ; 7, 0
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call _parseArgs
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ret nz
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; ok, now we can
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ld l, h ; k in L
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ld h, c ; bit in H
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.spitBR2:
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call readWord
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ret nz
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call parseExpr
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ret nz
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; IX contains an absolute value. Turn this into a -64/+63 relative
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; value by subtracting PC from it. However, before we do that, let's
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; add 0x7f to it, which we'll remove later. This will simplify bounds
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; checks. (we use 7f instead of 3f because we deal in bytes here, not
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; in words)
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push ix \ pop hl
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ld de, 0x7f
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add hl, de ; Carry cleared
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ex de, hl
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call zasmGetPC ; --> HL
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; The relative value is actually not relative to current PC, but to
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; PC after the execution of this branching op. Increase HL by 2.
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inc hl \ inc hl
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ex de, hl
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sbc hl, de
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jp c, unsetZ ; Carry? error
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ld de, 0x7f
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sbc hl, de
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; We're within bounds! However, our value in L is the number of
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; relative *bytes*. The value we put there is the number of words.
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; Thefore, relevant bits are 7:1
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; bit in H, k in L.
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; Our value in L is the number of relative *bytes*. The value we put
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; there is the number of words. Therefore, relevant bits are 7:1
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ld a, l
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sla a \ rl b
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sla a \ rl b
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and 0b11111000
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; k is now shifted by 3, two of those bits being in B. Let's OR A and
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; C and we have our LSB ready to go.
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or c
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; H and we have our LSB ready to go.
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or h
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call ioPutB
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; Good! MSB now. B is already good to go.
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ld a, b
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@ -417,10 +396,10 @@ parseInstruction:
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; upcode becomes 0b111101
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inc b
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.rdBRBS:
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call .readBit
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ret nz
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call readComma
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ld ix, argSpecs+10 ; bit + k(7)
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call _parseArgs
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ret nz
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; bit in H, k in L.
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jr .spitBR2
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; local routines
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@ -447,8 +426,141 @@ parseInstruction:
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ld hl, instrUpMasks2
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jp addHL
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.readR4:
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call .readR5
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; Argspecs: two bytes describing the arguments that are accepted. Possible
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; values:
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;
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; 0 - None
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; 7 - a k(7) address, relative to PC, *in bytes* (divide by 2 before writing)
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; 8 - a K(8) value
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; 'a' - A 5-bit I/O port value
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; 'A' - A 6-bit I/O port value
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; 'b' - a 0-7 bit value
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; 'R' - an r5 value: r0-r31
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; 'r' - an r4 value: r16-r31
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;
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; All arguments accept expressions, even 'r' ones: in 'r' args, we start by
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; looking if the arg starts with 'r' or 'R'. If yes, it's a simple 'rXX' value,
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; if not, we try parsing it as an expression and validate that it falls in the
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; correct 0-31 or 16-31 range
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argSpecs:
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.db 'R', 0 ; Rd(5)
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.db 'R', 'R' ; Rd(5) + Rr(5)
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.db 7, 0 ; k(7)
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.db 'r', 8 ; Rd(4) + K(8)
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.db 'R', 'b' ; Rd(5) + bit
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.db 'b', 7 ; bit + k(7)
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; Parse arguments in (HL) according to specs in IX
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; Puts the results in HL (which is not needed anymore after the parsing).
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; First arg in H, second in L.
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; This routine is not used in all cases, some ops don't fit this pattern well
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; and thus parse their args themselves.
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; Z for success.
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_parseArgs:
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; For the duration of the routine, our final value will be in DE, and
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; then placed in HL at the end.
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push de
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call readWord
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jr nz, .end
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ld a, (ix)
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call .parse
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jr nz, .end
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ld d, a
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ld a, (ix+1)
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or a
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jr z, .end ; no arg
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call readComma
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jr nz, .end
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call readWord
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jr nz, .end
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ld a, (ix+1)
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call .parse
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jr nz, .end
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; we're done with (HL) now
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ld l, a
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cp a ; ensure Z
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.end:
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ld h, d
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pop de
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ret
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; Parse a single arg specified in A and returns its value in A
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; Z for success
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.parse:
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cp 'R'
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jr z, _readR5
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cp 'r'
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jr z, _readR4
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cp 'b'
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jr z, _readBit
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cp 7
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jr z, _readk7
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cp 8
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jr z, _readK8
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ret ; something's wrong
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_readBit:
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push ix
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call parseExpr
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ld a, 7
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call _IX2A
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jr nz, .end
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or c
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ld c, a
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cp a ; ensure Z
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.end:
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pop ix
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ret
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_readk7:
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push hl
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push de
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push ix
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call parseExpr
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jr nz, .end
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; IX contains an absolute value. Turn this into a -64/+63 relative
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; value by subtracting PC from it. However, before we do that, let's
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; add 0x7f to it, which we'll remove later. This will simplify bounds
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; checks. (we use 7f instead of 3f because we deal in bytes here, not
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; in words)
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push ix \ pop hl
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ld de, 0x7f
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add hl, de ; Carry cleared
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ex de, hl
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call zasmGetPC ; --> HL
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; The relative value is actually not relative to current PC, but to
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; PC after the execution of this branching op. Increase HL by 2.
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inc hl \ inc hl
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ex de, hl
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sbc hl, de
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jp c, .err ; Carry? error
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ld de, 0x7f
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sbc hl, de
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; We're within bounds! However, our value in L is the number of
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; relative *bytes*.
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ld a, l
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cp a ; ensure Z
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.end:
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pop ix
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pop de
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pop hl
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ret
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.err:
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call unsetZ
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jr .end
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_readK8:
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push ix
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call parseExpr
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jr nz, .end
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ld a, 0xff
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call _IX2A
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.end:
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pop ix
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ret
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_readR4:
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call _readR5
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ret nz
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; has to be in the 16-31 range
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sub 0x10
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@ -458,34 +570,25 @@ parseInstruction:
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; read a rXX argument and return register number in A.
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; Set Z for success.
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.readR5:
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call readWord
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_readR5:
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push ix
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ld a, (hl)
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call upcase
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cp 'R'
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ret nz ; not a register
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jr nz, .end ; not a register
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inc hl
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call parseDecimal
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ret nz
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jr nz, .end
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ld a, 31
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jr .IX2A
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.readBit:
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call readWord
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ret nz
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call parseExpr
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ld a, 7
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call .IX2A
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ret nz
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or c
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ld c, a
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cp a ; ensure Z
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call _IX2A
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.end:
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pop ix
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ret
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; Put IX's LSB into A and, additionally, ensure that the new value is <=
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; than what was previously in A.
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; Z for success.
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.IX2A:
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_IX2A:
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push ix \ pop hl
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cp l
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jp c, unsetZ ; A < L
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@ -495,3 +598,5 @@ parseInstruction:
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ld a, l
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; Z set from "or a"
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ret
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@ -80,8 +80,10 @@ ioGetB:
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call ioInInclude
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jr z, .normalmode
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; We're in "include mode", read from FS
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push ix ; --> lvl 1
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ld ix, IO_INCLUDE_BLK
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call _blkGetB
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pop ix ; <-- lvl 1
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jr nz, .includeEOF
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cp 0x0a ; newline
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ret nz ; not newline? nothing to do
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@ -111,9 +113,11 @@ ioGetB:
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; continue on to "normal" reading. We don't want to return our zero
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.normalmode:
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; normal mode, read from IN stream
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push ix ; --> lvl 1
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ld ix, IO_IN_BLK
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call _blkGetB
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cp 0x0a ; newline
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pop ix ; <-- lvl 1
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cp LF ; newline
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ret nz ; not newline? return
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; inc current lineno
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push hl
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@ -130,10 +134,6 @@ ioGetB:
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pop af
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ret
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_callIX:
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jp (ix)
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ret
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; Put back non-zero character A into the "ioGetB stack". The next ioGetB call,
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; instead of reading from IO_IN_BLK, will return that character. That's the
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; easiest way I found to handle the readWord/gotoNextLine problem.
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@ -155,8 +155,7 @@ readComma:
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cp ','
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ret z
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call ioPutBack
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call unsetZ
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ret
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jp unsetZ
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; Read ioGetB until we reach the beginning of next line, skipping comments if
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; necessary. This skips all whitespace, \n, \r, comments until we reach the
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