EM78系列單片機(jī)的一些關(guān)于數(shù)值轉(zhuǎn)換的子程序

1、EM78系列單片機(jī)的一些關(guān)于數(shù)值轉(zhuǎn)換的子程序一 二進(jìn)制數(shù)轉(zhuǎn)換為ASC碼將一個(gè)字節(jié)的二進(jìn)制數(shù)轉(zhuǎn)換為兩位16進(jìn)制數(shù)的ASC碼main: mov a,0x9f ;二進(jìn)制數(shù)為0x9fmov 0x30,a ;二進(jìn)制數(shù)存入0x30mov a,0x02mov 0x10,a ;0x10中存放轉(zhuǎn)換次數(shù)mov a,0x31mov 0x04,a ;0x04中為轉(zhuǎn)換后數(shù)據(jù)存放地址mov a,0x30B1: and a,0x0f ;取a低4位mov 0x00,asub a,0x09 ;低4位大于9跳往B2jbs 0x03,0jmp B2mov a,0x00 ;低4位不大于9則加0x30add a,0x30mov 0x0

2、0,a ;將ASC碼存入0X04所指單元jmp B3B2: mov a,0x00 ;大于9則加0X37add a,0x37mov 0x00,aB3: swapa 0x30 ;將0X30高4位換入A低4位inc 0x04 ;存儲(chǔ)地址加1djz 0x10 ;循環(huán)次數(shù)減1,為0則返回jmp B1 ;不為0繼續(xù)轉(zhuǎn)換 self: jmp selfeop二 多字節(jié)二進(jìn)制加法0X20,0X21中的二進(jìn)制無(wú)符號(hào)數(shù)與0X22,0X23中的二進(jìn)制無(wú)符號(hào)數(shù)相加,結(jié)果放在0X24,0X25,0X26中,低地址中放低字節(jié)數(shù)據(jù)。Main： mov a，0x78 ;賦值mov 0x20,amov a,0xc6mov 0x2

3、1,amov a,0x86mov 0x22,amov a,0x9emov 0x23,amov a,0x0 ;0x26單元清0mov 0x26,amov a,0x21add a,0x23mov 0x25,a ;高字節(jié)相加,結(jié)果送0x25jbc 0x03,0inc 0x26 ; 有進(jìn)位則0x26加1mov a,0x20add a,0x22mov 0x24,a ;低字節(jié)相加,結(jié)果送0x24jbs 0x03,0jmp self ;無(wú)進(jìn)位跳selfinc 0x25 ;有進(jìn)位0x25加1jbc 0x03,0inc 0x26 ; 有進(jìn)位0x26加1self: jmp selfeop三 多字節(jié)二進(jìn)制減法0x2

4、0,0x21中的二進(jìn)制無(wú)符號(hào)數(shù)減0x22,0x23中的二進(jìn)制無(wú)符號(hào)數(shù), 低地址中放低字節(jié)數(shù)據(jù)。假設(shè)被減數(shù)大于減數(shù)。注意：（1）sub指令減出結(jié)果為正時(shí)，c標(biāo)志置1。（2）sub指令減出結(jié)果為0時(shí)，c標(biāo)志也置1。即，sub指令執(zhí)行后，c標(biāo)志清0表示結(jié)果為負(fù)。main： mov a，0x67 ;賦值mov 0x20,amov a,0xffmov 0x21,amov a,0xe8mov 0x22,amov a,0x44mov 0x23,a ; 高字節(jié)相減sub a,0x21mov 0x25,a ;結(jié)果存0x25mov a,0x22 ;低字節(jié)相減sub a,0x20mov 0x24,ajbs 0x03

5、,0dec 0x25 ;有借位則0x25減1self: jmp selfeop四 二進(jìn)制乘法運(yùn)算EM78單片機(jī)沒(méi)有乘法指令,所以乘法運(yùn)算需要轉(zhuǎn)化為加法運(yùn)算。0X20單元數(shù)據(jù)乘以0X21單元數(shù)據(jù)，結(jié)果放在0X22，0X23中。main: mov a,0x0 ;0x22,0x23單元清0mov 0x22,amov 0x23,amov a,0x3f ;賦值mov 0x20,amov a,0x22mov 0x21,amul1: mov a,0x20 ；0x20與0x22內(nèi)容相加add 0x22,ajbc 0x03,0inc 0x23 ;有進(jìn)位0x23加1djz 0x21 ;0x21中次數(shù)減到0則結(jié)束j

6、mp mul1 ;沒(méi)減到0則繼續(xù)self: jmp selfeop五 二進(jìn)制除法運(yùn)算多字節(jié)二進(jìn)制除法被除數(shù)為3個(gè)字節(jié)，在0x20、0x21、0x22單元中，0x22.7為最高位，0x20.0為最低位。除數(shù)為2個(gè)字節(jié)，在0x30、0x31中。算法：EM78單片機(jī)沒(méi)有除法指令，而且本例中除法為多字節(jié)除法，可采用如下算法。將被除數(shù)擴(kuò)充一個(gè)字節(jié)0X23，0X23清0。被除數(shù)左移1位，0X23、0X22中數(shù)據(jù)減去0X31、0X30中數(shù)據(jù)，夠減則減且0X20.0置1，減出結(jié)果存入0X23、0X22；不夠減則0X23、0X22保持不變，0X20.0清0。然后被除數(shù)再左移1位，重復(fù)上述過(guò)程。共循環(huán)16次，最后

7、0X23、0X22中得相減余數(shù)，0X21、0X20中得商。注意，若被除數(shù)左移后C標(biāo)志為1，則不比較0X23、0X22與0X31、0X30數(shù)據(jù)大小關(guān)系而直接相減。main： mov a,0x55 ;被除數(shù)賦值mov 0x20,amov 0x21,amov 0x22,amov a,0x0 ;被除數(shù)擴(kuò)充1字節(jié)并清0mov 0x23,amov a,0x12 ;除數(shù)賦值mov 0x30,amov 0x31,amov a,0x10 ;循環(huán)次數(shù)為16mov 0x32,aagain: call rt_sub ;調(diào)移位除法子程djz 0x32 ;16次循環(huán)完成則結(jié)束jmp again ;未完成則繼續(xù)self:

8、jmp selfrt_sub:bc 0x03,0 ;c標(biāo)志清0rlc 0x20 ;被除數(shù)左移1位rlc 0x21rlc 0x22rlc 0x23jbc 0x03,0jmp rt3 ;c標(biāo)志為1則直接相減mov a,0x23 ;c標(biāo)志為0則先比較大小mov 0x25,amov a,0x22mov 0x24,amov a,0x31 ;先比較高位sub 0x25,ajbc 0x03,2jmp rt1 ;高位相等跳rt1比較低位jmp rt2 ;高位不等跳rt2rt1: mov a,0x30 ;比較低位sub 0x24,ajbc 0x03,2jmp rt3 ;低位也相等則跳rt3,相減,上1rt2:

9、jbs 0x03,0ret ;減數(shù)大則返回,減數(shù)小則相減,上1rt3: bs 0x20,0 ;上1call sub_2b ;調(diào)2字節(jié)減法子程retsub_2b:mov a,0x31 ;高字節(jié)相減sub 0x23,amov a,0x30 ;低字節(jié)相減sub 0x22,ajbc 0x03,2ret ;低字節(jié)相等,無(wú)借位,返回jbc 0x03,0ret ;無(wú)借位,返回dec 0x23 ;低字節(jié)相減有借位,高字節(jié)結(jié)果減1reteop六 BCD數(shù)轉(zhuǎn)換為二進(jìn)制數(shù)兩字節(jié)壓縮BCD碼轉(zhuǎn)換為兩字節(jié)二進(jìn)制數(shù)。算法如下：BCD碼abcd=1000a+100b+10c+d=101010a+b+c+d，將各位BCD碼分

10、離出之后，即可根據(jù)此式轉(zhuǎn)換為二進(jìn)制數(shù)。涉及到乘法運(yùn)算和多字節(jié)加法運(yùn)算。0X20，0X21中為BCD碼，0X21高4位為最高位。轉(zhuǎn)換結(jié)果放在0X30，0X31中。main： mov a，0x79mov 0x20,amov a,0x54mov 0x21,a ;賦值mov a,0x20and a,0x0fmov 0x22,aswapa 0x20and a,0x0fmov 0x23,amov a,0x21and a,0x0fmov 0x24,aswapa 0x21and a,0x0fmov 0x25,a ;BCD碼展開(kāi)后存于0X22,0X23,0X24,0X25mov a,0x25, ;0X25為最高

11、位mov 0x30,amov a,0x0 ;多字節(jié)加法高位為0mov 0x31,amov a,0x24mov 0x32,acall a_b ;調(diào)子程mov a,0x23mov 0x32,acall a_bmov a,0x22mov 0x32,acall a_bself: jmp selfa_b:mov a,0x0 ;0X34,0X35存儲(chǔ)中間結(jié)果mov 0x34,amov 0x35,amov a,0x0a ;實(shí)現(xiàn)乘10mov 0x33,aa1: mov a,0x35 ;兩字節(jié)二進(jìn)制加法,在本例中高字節(jié)肯定無(wú)進(jìn)位add a,0x31mov 0x35,amov a,0x34add a,0x30mo

12、v 0x34,ajbc 0x03,0inc 0x35djz 0x33jmp a1mov a,0x32add 0x34,ajbc 0x03,0inc 0x35mov a,0x34mov 0x30,amov a,0x35mov 0x31,areteop七 二進(jìn)制數(shù)轉(zhuǎn)換為BCD碼本例為單字節(jié)二進(jìn)制數(shù)(0X20)轉(zhuǎn)換為非壓縮BCD碼,存在0X25,0X24,0X23中,0X25為百位,0X23為個(gè)位。main: mov a,0xa4 ;賦值mov 0x20,amov 0x21,amov 0x22,amov a,0x0 ;0x23,0x24,0x25單元清0mov 0x23,amov 0x24,amov 0x25,amov a,0x64 ;對(duì)100的個(gè)數(shù)計(jì)數(shù)mov 0x26,amov a,0x25 ;百位存在0x25中mov 0x04,acall a0 ;調(diào)計(jì)數(shù)子程mov a,0x0a ;對(duì)10的個(gè)數(shù)計(jì)數(shù)mov 0x26,adec 0x04 ;個(gè)位存在0x24中call a0mov a,0x22 ;除去百位,十位,余下的即個(gè)位,存入0x23mov 0x23,aself: jmp selfa0: ;計(jì)數(shù)子程mov a,0x26sub 0x22,ajbs 0x03,2jmp a1inc 0x00 ;無(wú)余