From edbd77564203dfdb651496f7a467ed6fee30e443 Mon Sep 17 00:00:00 2001 From: Clanmaster21 Date: Mon, 21 Oct 2019 02:13:21 +0100 Subject: [PATCH] Fixed more errors, clearer choice of constants --- apps/lib/parse.asm | 21 ++++++++------------- 1 file changed, 8 insertions(+), 13 deletions(-) diff --git a/apps/lib/parse.asm b/apps/lib/parse.asm index d561311..6c281d3 100644 --- a/apps/lib/parse.asm +++ b/apps/lib/parse.asm @@ -9,28 +9,23 @@ ; On success, the carry flag is reset. On error, it is set. ; Also, zero flag set if '0' ; parseDecimalDigit has been replaced with the following code inline: -; add a, 0xc6 ; Maps '0'-'9' onto 0xf6-0xff -; sub 0xf6 ; Anything but 0xf6-0xff carries - ; Maps 0xf6-0xff onto 0-9 +; add a, 0xff-'9' ; maps '0'-'9' onto 0xf6-0xff +; sub 0xff-9 ; maps to 0-9 and carries if not a digit ; Parse string at (HL) as a decimal value and return value in IX under the ; same conditions as parseLiteral. ; Sets Z on success, unset on error. -; 61 bytes -; 107 cycles overhead + up to 73 cycles if length >= 5 -; 136 cycles in loop -; first digit is skipped in overhead parseDecimal: push hl ld a, (hl) - add a, 0xc6 ; converts '0'-'9' to 0-9 - sub 0xf6 ; carries if out of range + add a, 0xff-'9' ; maps '0'-'9' onto 0xf6-0xff + sub 0xff-9 ; maps to 0-9 and carries if not a digit exx ; preserve bc, hl, de ld h, 0 ld l, a ; load first digit in without multiplying - ld b, 4 ; Carries can only occur for decimals >=5 in length + ld b, 3 ; Carries can only occur for decimals >=5 in length jr c, .error .loop: @@ -39,8 +34,8 @@ parseDecimal: ld a, (hl) exx - add a, 0xc6 ; converts '0'-'9' to 0-9 - sub 0xf6 ; carries if out of range + add a, 0xff-'9' ; maps '0'-'9' onto 0xf6-0xff + sub 0xff-9 ; maps to 0-9 and carries if not a digit jr c, .error add hl, hl ; x2 @@ -68,7 +63,7 @@ parseDecimal: inc hl ld a, (hl) exx - add a, 0xd0 + add a, 0xd0 ; the next line expects a null to be mapped to 0xd0 .error: sub 0xd0 ; if a is null, set Z ; a is checked for null before any errors