6502/cc65
1
0
Fork 0
mirror of https://github.com/cc65/cc65.git synced 2025-04-06 20:37:16 +00:00
Code Issues Projects Releases Wiki Activity

Rewrite asctime() in assembler (-7 bytes)

Browse Source
This commit is contained in:
Colin Leroy-Mira 2024-01-10 22:26:55 +01:00
parent 03d5e5fba0
commit 10282a9b74
2 changed files with 81 additions and 59 deletions
libsrc/common
asctime.casctime.s

59
libsrc/common/asctime.c

@ -1,59 +0,0 @@
/*****************************************************************************/
/* */
/* asctime.c */
/* */
/* Convert a broken down time into a string */
/* */
/* */
/* */
/* (C) 2002 Ullrich von Bassewitz */
/* Wacholderweg 14 */
/* D-70597 Stuttgart */
/* EMail: uz@musoftware.de */
/* */
/* */
/* This software is provided 'as-is', without any expressed or implied */
/* warranty. In no event will the authors be held liable for any damages */
/* arising from the use of this software. */
/* */
/* Permission is granted to anyone to use this software for any purpose, */
/* including commercial applications, and to alter it and redistribute it */
/* freely, subject to the following restrictions: */
/* */
/* 1. The origin of this software must not be misrepresented; you must not */
/* claim that you wrote the original software. If you use this software */
/* in a product, an acknowledgment in the product documentation would be */
/* appreciated but is not required. */
/* 2. Altered source versions must be plainly marked as such, and must not */
/* be misrepresented as being the original software. */
/* 3. This notice may not be removed or altered from any source */
/* distribution. */
/* */
/*****************************************************************************/
#include <stdio.h>
#include <time.h>
/*****************************************************************************/
/* Code */
/*****************************************************************************/
/*
CAUTION: we need to reserve enough space to be able to hold the maximum
length string:
1234567890123456789012345678901234567
"Wednesday September ..1 00:00:00 1970"
*/
char* __fastcall__ asctime (const struct tm* timep)
{
static char buf[38];
/* Format into given buffer and return the result */
return strftime (buf, sizeof (buf), "%c\n", timep)? buf : 0;
}

81
libsrc/common/asctime.s Normal file

@ -0,0 +1,81 @@
;
; Colin Leroy-Mira, 2024
;
; char* __fastcall__ asctime (const struct tm* timep)
;
.export _asctime
.import _strftime, pushax
.importzp ptr1
.include "time.inc"
.macpack cpu
; ------------------------------------------------------------------------
; Special values
; We need to be able to store up to 38 bytes:
; 1234567890123456789012345678901234567
; "Wednesday September ..1 00:00:00 1970"
MAX_BUF_LEN = 38
; ------------------------------------------------------------------------
; Code
_asctime:
; Backup timep
.if (.cpu .bitand ::CPU_ISET_65SC02)
pha
phx
.else
sta ptr1
stx ptr1+1
.endif
; Push buf
lda #<buf
ldx #>buf
jsr pushax
; Push sizeof(buf)
lda #<MAX_BUF_LEN
ldx #>MAX_BUF_LEN
jsr pushax
; Push format string
lda #<fmt
ldx #>fmt
jsr pushax
; Restore timep
.if (.cpu .bitand ::CPU_ISET_65SC02)
plx
pla
.else
lda ptr1
ldx ptr1+1
.endif
; Call formatter
jsr _strftime
; Check return status
bne :+
cpx #$00
bne :+
rts
: lda #<buf
ldx #>buf
rts
.data
fmt: .byte '%'
.byte 'c'
.byte $0A
.byte $00
.bss
buf: .res MAX_BUF_LEN