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mirror of https://github.com/hsoft/collapseos.git synced 2024-12-24 14:28:06 +11:00

lib/expr: refactor for easier operator addition

This commit is contained in:
Virgil Dupras 2019-11-22 14:45:12 -05:00
parent fd5b2ab856
commit 1b01f13105
9 changed files with 95 additions and 47 deletions

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@ -25,3 +25,20 @@ divide:
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

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@ -23,16 +23,30 @@ parseExpr:
ret
_parseExpr:
ld a, '+'
ld de, exprTbl
.loop:
ld a, (de)
or a
jp z, EXPR_PARSE ; no operator, just parse the literal
push de ; --> lvl 1. save operator row
call _findAndSplit
jp z, _applyPlus
ld a, '-'
call _findAndSplit
jp z, _applyMinus
ld a, '*'
call _findAndSplit
jp z, _applyMult
jp EXPR_PARSE
jr z, .found
pop de ; <-- lvl 1
inc de \ inc de \ inc de
jr .loop
.found:
; Operator found, string splitted. Left in (HL), right in (DE)
call _resolveLeftAndRight
; Whether _resolveLeftAndRight was a success, we pop our lvl 1 stack
; out, which contains our operator row. We pop it in HL because we
; don't need our string anymore. L-R numbers are parsed, and in DE and
; IX.
pop hl ; <-- lvl 1
ret nz
; Resolving left and right succeeded, proceed!
inc hl ; point to routine pointer
call intoHL
jp (hl)
; Given a string in (HL) and a separator char in A, return a splitted string,
; that is, the same (HL) string but with the found A char replaced by a null
@ -88,20 +102,25 @@ _resolveLeftAndRight:
pop de ; numeric left expr result in DE
jp parseExpr
; Parse expr in (HL) and expr in (DE) and apply + operator to both sides.
; Put result in IX.
_applyPlus:
call _resolveLeftAndRight
ret nz
; Good! let's do the math! IX has our right part, DE has our left one.
; Routines in here all have the same signature: they take two numbers, DE (left)
; and IX (right), apply the operator and put the resulting number in IX.
; The table has 3 bytes per row: 1 byte for operator and 2 bytes for routine
; pointer.
exprTbl:
.db '+'
.dw .plus
.db '-'
.dw .minus
.db '*'
.dw .mult
.db 0 ; end of table
.plus:
add ix, de
cp a ; ensure Z
ret
; Same as _applyPlus but with -
_applyMinus:
call _resolveLeftAndRight
ret nz
.minus:
push ix
pop hl
ex de, hl
@ -112,9 +131,7 @@ _applyMinus:
cp a ; ensure Z
ret
_applyMult:
call _resolveLeftAndRight
ret nz
.mult:
push ix \ pop bc
call multDEBC
push hl \ pop ix

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@ -73,20 +73,3 @@ strlen:
pop hl
pop bc
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

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@ -66,6 +66,7 @@ jp zasmMain
.inc "core.asm"
.inc "zasm/const.asm"
.inc "lib/util.asm"
.inc "lib/ari.asm"
.inc "lib/parse.asm"
.inc "lib/args.asm"
.inc "zasm/util.asm"

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@ -3,6 +3,7 @@ jp test
.inc "core.asm"
.inc "str.asm"
.inc "lib/util.asm"
.inc "lib/ari.asm"
.inc "lib/parse.asm"
.equ EXPR_PARSE parseLiteral
.inc "lib/expr.asm"

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@ -12,6 +12,7 @@ jp test
.inc "core.asm"
.inc "str.asm"
.inc "lib/util.asm"
.inc "lib/ari.asm"
.inc "zasm/util.asm"
.inc "zasm/const.asm"
.inc "lib/parse.asm"

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@ -0,0 +1,35 @@
jp test
.inc "core.asm"
.inc "lib/ari.asm"
testNum: .db 1
test:
ld sp, 0xffff
ld de, 12
ld bc, 4
call multDEBC
ld a, l
cp 48
jp nz, fail
call nexttest
; success
xor a
halt
nexttest:
ld a, (testNum)
inc a
ld (testNum), a
ret
fail:
ld a, (testNum)
halt

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@ -12,14 +12,6 @@ test:
ld hl, 0xffff
ld sp, hl
ld de, 12
ld bc, 4
call multDEBC
ld a, l
cp 48
jp nz, fail
call nexttest
ld hl, sFoo
call strlen
cp 3

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@ -4,6 +4,7 @@ jp runTests
.inc "core.asm"
.inc "str.asm"
.inc "zasm/const.asm"
.inc "lib/ari.asm"
.inc "lib/util.asm"
.inc "zasm/util.asm"
.inc "lib/parse.asm"