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

zasm: add support for hex literals

This commit is contained in:
Virgil Dupras 2019-05-09 22:14:11 -04:00
parent b87feac785
commit 5a6078df4d
4 changed files with 65 additions and 7 deletions

View File

@ -2,7 +2,7 @@
; result in A.
;
; On success, the carry flag is reset. On error, it is set.
parseDecimal:
parseDecimalDigit:
; First, let's see if we have an easy 0-9 case
cp '0'
ret c ; if < '0', we have a problem
@ -12,10 +12,9 @@ parseDecimal:
ccf ; invert C flag
ret
; Parses the string at (HL) and returns the 16-bit value in IX.
; 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.
parseNumber:
; Parse string at (HL) as a decimal value and return value in IX under the
; same conditions as parseNumber.
parseDecimal:
push hl
push de
push bc
@ -25,7 +24,7 @@ parseNumber:
ld a, (hl)
cp 0
jr z, .end ; success!
call parseDecimal
call parseDecimalDigit
jr c, .error
; Now, let's add A to IX. First, multiply by 10.
@ -58,3 +57,59 @@ parseNumber:
pop de
pop hl
ret
; Parse string at (HL) as a hexadecimal value and return value in IX under the
; same conditions as parseNumber.
parseHexadecimal:
push hl
xor a
ld ixh, a
inc hl ; get rid of "0x"
inc hl
call strlen
cp 3
jr c, .single
cp 5
jr c, .double
; too long, error
jr .error
.double:
call JUMP_PARSEHEXPAIR ; moves HL to last char of pair
jr c, .error
inc hl ; now HL is on first char of next pair
ld ixh, a
.single:
call JUMP_PARSEHEXPAIR
jr c, .error
ld ixl, a
cp a ; ensure Z
jr .end
.error:
call JUMP_UNSETZ
.end:
pop hl
ret
; Sets Z if (HL) has a '0x' or '0X' prefix.
hasHexPrefix:
ld a, (hl)
cp '0'
ret nz
push hl
inc hl
ld a, (hl)
cp 'x'
jr z, .end
cp 'X'
.end:
pop hl
ret
; Parses the string at (HL) and returns the 16-bit value in IX.
; 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.
parseNumber:
call hasHexPrefix
jr z, parseHexadecimal
jr parseDecimal

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@ -5,7 +5,8 @@ label1:
; comment
.db 42
label2:
.dw 42
.dw 0x42
.dw 3742
.dw 0x3742
ld a, (label1)
ld hl, label2

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@ -12,6 +12,7 @@ jp upcase
jp unsetZ
jp intoDE
jp findchar
jp parseHexPair
init:
di

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@ -6,6 +6,7 @@ JUMP_UPCASE .equ 0x0b
JUMP_UNSETZ .equ 0x0e
JUMP_INTODE .equ 0x11
JUMP_FINDCHAR .equ 0x14
JUMP_PARSEHEXPAIR .equ 0x17
.equ USER_CODE 0x4000
.equ RAMSTART 0x6000