LDR r1, =0x20026; SWI 0x123456;ARM semihosting SWI func1 LDR r0, =42; 可以转换成MOV格式=> MOV R0, #42 LDR r1, =0x55555555;不能转换,因为超过了MOV操作数的范围,故用literal pool => LDR R1, [PC,#offset to Literal Pool 1] LDR r2, =0xFFFFFFFF;可以转换成MVN =>MVN R2, #0 MOV ...
LDR r1, =0x20026; SWI 0x123456;ARM semihosting SWI func1 LDR r0, =42; 可以转换成MOV格式=> MOV R0, #42 LDR r1, =0x55555555;不能转换,因为超过了MOV操作数的范围,故用literal pool => LDR R1, [PC,#offset to Literal Pool 1] LDR r2, =0xFFFFFFFF;可以转换成MVN =>MVN R2, #0 MOV ...
;两个64位数相加,第一个64位的低32位放在 r0,高位放到 r1,第二个64位数的低32位放在 r2 高32位放在 r3;编写代码实现两个64位数的和,结果的低32位放在 r4 高32位放在 r5 mov r0,#0xfffffffe;第一个数的低32位 mov r1,#1;第一个数的高32位 mov r2,#0x5;第二个数的低32位 mov r3,#1;第...
MOV R0,#0x8000 MOV R2,#0x0 STR R2,[R0] MOV R1,#0x000003F0 SWPB R4,R1,[R0] 执行完以上汇编程序后,R4和[R0]的结果是多少 A. R4=0x40 [R0]=0x06F0 B. R4=0x3F0 [R0]=0x8000 C. R4=0x40 [R0]=0x8000 D. R4=0x3F0 [R0]=0x06F0 ...
Product:Varistor;Termination Style:Radial;Voltage Rating AC:10V-510V;Voltage Rating DC:14V-670V;Varistor Voltage:18V-820V;Part number:VDRS07B040TLE;Peak Surge Current:1200A;Operating Temperature:-40C to +105C;Packaging:Bulk or Ammo;Tolerance:0.1;Type:M
另外,在《arm体系结构与编程》这本书里,并没有说立即数的具体范围,在26页有一句:mov r0, #0xfc0明显立即数大于255了。在144页有提到,“ldr伪指令读取的数据超过mov操作范围”。这说明mov可操作的立即数是有一定范围的,且比ldr小。再来分析一下立即数的产生,其寻址方式是这样的:11??? 8 7 ? ? ? ? ?
LDR R0,=0xff 这里的LDR不是arm指令,而是伪指令。这个时候与MOVE很相似,只不过MOV指令后的立即数是有限制的。这个立即数必须是0X00-OXFF范围内的数经过偶数次右移得到的数,所以MOV用起来比较麻烦,因为有些数不那么容易看出来是否合法。
Data1p DCD 0, 0 ;just happen the address is at 0x40000000 ;DCD (reserve a 32-bit word)is a pseudo instruction to ;allocate a memory location for this data. align align : : Statment1 LDR R0, =Data1p ; Put the address Data1p into R0 ...
Ldr R0, 0x12345678 is to store the value of the 0x12345678 address in the r0. And MOV can not do this job, MOV can only move data between registers, or to move the number of immediate to register, this and x86 this CISC architecture chip difference is the biggest place. ...
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