>From News server: news.freesoft.cei.gov.cn From: "Miao YuCheng" <[EMAIL PROTECTED]> Newsgroups: chinese.comp.linux.development Subject: 也談漢字的快速顯示 Date: Fri, 17 Dec 1999 22:30:33 +0800
[posted and mailed] On 17 Dec 1999, you wrote in chinese.comp.linux.development: >最近正在看Michael Abrash's Graphics Programming黑皮書, >深受啟發. 聯系以前對yact, [EMAIL PROTECTED], 做了 >[EMAIL PROTECTED], 發現如果用寫模式3避開out指令的話, 可以使單字 >顯示的速度明顯加快. [EMAIL PROTECTED], 用通常意義上的快速方 >法, 即通過每次寫位屏蔽寄存器顯示8個pixel的方案最少也要 >15000microseconds(1 microseconds = 1000 ns), 而用寫模 >式3可以達到5000microsends的速度以單字顯示調用寫滿全屏 >([EMAIL PROTECTED] >幕, 也就是包括了push, pop的時間, [EMAIL PROTECTED] >會[EMAIL PROTECTED]). 如果說寫模式3用的不多的原因在于和EGA不兼容 >的話, 那么按照現在VGA如此普及的情形, 我想該不用再考慮和 >EGA間的兼容性了吧. 我修改了cce中的顯示ascii字符的過程, >重新編譯后, [EMAIL PROTECTED] >ASCII ART 文件, 比如earth([EMAIL PROTECTED], >還有許多其他好玩的東西, 如聖誕動畫等, 很經典), >速度明顯快了許多, 和gce相比還是快(想來, gce不會是用寫模 >式3顯示字符的). [EMAIL PROTECTED] >有明顯的速度增加, cce之所以慢看來要歸咎于卷屏的問題了, >cce通過拷貝顯存實現卷屏, 約要占去40000microseconds的時 >間, [EMAIL PROTECTED], 優化后速度無怪沒有明顯的增加. >考慮用起始行掃描寄存器(估計gce也是這么做的), 還是有些問 >題的, [EMAIL PROTECTED], 約只能卷18行, 18行后還 >[EMAIL PROTECTED], 如果能避免, 當然最好. >二是用起始掃描寄存器的話, 每次卷屏, 都要重畫狀態條, 該 >如何避免? 拆分屏幕是否能解決此問題. 如果上述兩者都不能 >避免的話, [EMAIL PROTECTED], 每卷屏18行, 平均每次卷屏所化時間 >4500microseconds, 雖然還是遠遠小于cce的時間, 但卻不是 >最理想的. 我在這里討論, 希望有過漢字或圖形編程經驗的朋 >友能說說解決之道. > >另附利用寫模式3實現單字顯示的過程: >#void hz16_draw (int row, int col, char** hzbm); >#row -- 行 >#col -- 列 >#hzbm - 漢字位圖 > >hz16_draw: > pushl %ebp > movl %esp, %ebp > pushl %ecx > pushl %edx > pushl %esi > pushl %edi > > # 用offset_table表的方法增加速度, > # 等效于下面注釋的代碼 > movl 8(%ebp), %eax > shll $2, %eax > movl offset_table(%eax), %edi > movl 12(%ebp),%edx > shll $1, %edx > addl %edx, %edi > > # simpliest but slowest > # movl 8(%ebp), %eax > # imul $1440, %eax > # movl %eax, %edi > > movl 16(%ebp), %esi > addl graph_mem, %edi > > #draw background > movw $0x3CE, %dx > movw $0xf00, %ax # replace 0xf with background > outw %ax, %dx > > movw $0xffff, (%edi) > > #draw foreground > movw $0x0000, %ax # replace 0x0 with foreground > outw %ax, %dx > > # [EMAIL PROTECTED], [EMAIL PROTECTED] > # 節約2000microseconds :-) > movw (%edi), %ax > movl $18, %ecx >draw2: > movw (%esi), %ax > movw %ax, (%edi) > addl $80, %edi > inc %esi > inc %esi > loop draw2 > > popl %edi > popl %esi > popl %edx > popl %ecx > popl %ebp > ret > > > > -- [ [EMAIL PROTECTED] is the mailing-list that ] [ this mail was originally sent to, and was forwarded to this list ] [ automatically. GB characters are also converted to Big5 at the same ] [ time. Note that there may be errors during the conversion as this ] [ is not done by a human! ]
