如何从寄存器中提取位中的值，并用它们替换其他寄存器中的位? (MIP汇编语言)

合并步骤(3):现在，我们合并移位后的值:yval |= xshf就这样-我们完成了... 原型:这是一些结合了所有这些内容的C代码.因为位范围值是固定的 ，所以掩码值是一次预先计算的.如果必须更改，则掩码代码将必须在每次合并调用时重新计算它们.还要注意，掩码是常量，因为范围是固定的.#include <stdio.h>#include <stdlib.h>int opt_v;typedef unsigned int u32;u32 xval;#define XHI 22#define XLO 4u32 yval;#define YHI 24#define YLO 6u32 xrmsk;u32 xlmsk;u32 yrmsk;u32 ylmsk;#define WID(__lo) (((_hi) - (_lo)) + 1)#define RMSK(__lo) (0xFFFFFFFF >> (32 - WID(__lo)))#define LMSK(__lo) (RMSK(__lo) << (_lo))#define SHOW(_sym) \ show(_sym,#_sym)#define SHOWX(_sym) \ if (opt_v) \ SHOW(_sym)voidshow(u32 val,const char *sym){ u32 bitmsk; u32 bitval; printf("%8.8X ",val); for (bitmsk = 1u << 31; bitmsk != 0; bitmsk >>= 1) { bitval = val & bitmsk; printf("%d",bitval ? 1 : 0); } printf(" %s\n",sym);}voidmerge(void){ u32 xshf; SHOW(xval); SHOW(yval); // extract (1): xshf = xval >> XLO; SHOW(xshf); // extract (2): SHOWX(xrmsk); xshf &= xrmsk; SHOW(xshf); // extract (3): xshf >>= 1; SHOW(xshf); // merge (1): SHOWX(yrmsk); SHOWX(ylmsk); yval &= ~ylmsk; SHOW(yval); // merge (2): xshf &= yrmsk; // belt and ... SHOW(xshf); xshf <<= YLO; SHOW(xshf); xshf &= ylmsk; // ... suspenders SHOW(xshf); // merge (3) yval |= xshf; SHOW(yval);}voidtest(u32 y,u32 x){ printf("\n"); yval = y; xval = x; merge();}// main -- main programintmain(int argc,char **argv){ char *cp; --argc; ++argv; for (; argc > 0; --argc, ++argv) { cp = *argv; if (*cp != '-') break; switch (cp[1]) { case 'v': opt_v = ! opt_v; break; default: break; } } xrmsk = RMSK(XHI,XLO); SHOW(xrmsk); xlmsk = LMSK(XHI,XLO); SHOW(xlmsk); yrmsk = RMSK(YHI,YLO); SHOW(yrmsk); ylmsk = LMSK(YHI,YLO); SHOW(ylmsk); test(0,~0); test(~0,0); for (int idx = 0; idx <= 5; ++idx) test(rand(),rand()); return 0;} 输出: 0007FFFF 00000000000001111111111111111111 xrmsk007FFFF0 00000000011111111111111111110000 xlmsk0007FFFF 00000000000001111111111111111111 yrmsk01FFFFC0 00000001111111111111111111000000 ylmskFFFFFFFF 11111111111111111111111111111111 xval00000000 00000000000000000000000000000000 yval0FFFFFFF 00001111111111111111111111111111 xshf0007FFFF 00000000000001111111111111111111 xshf0003FFFF 00000000000000111111111111111111 xshf00000000 00000000000000000000000000000000 yval0003FFFF 00000000000000111111111111111111 xshf00FFFFC0 00000000111111111111111111000000 xshf00FFFFC0 00000000111111111111111111000000 xshf00FFFFC0 00000000111111111111111111000000 yval00000000 00000000000000000000000000000000 xvalFFFFFFFF 11111111111111111111111111111111 yval00000000 00000000000000000000000000000000 xshf00000000 00000000000000000000000000000000 xshf00000000 00000000000000000000000000000000 xshfFE00003F 11111110000000000000000000111111 yval00000000 00000000000000000000000000000000 xshf00000000 00000000000000000000000000000000 xshf00000000 00000000000000000000000000000000 xshfFE00003F 11111110000000000000000000111111 yval6B8B4567 01101011100010110100010101100111 xval327B23C6 00110010011110110010001111000110 yval06B8B456 00000110101110001011010001010110 xshf0000B456 00000000000000001011010001010110 xshf00005A2B 00000000000000000101101000101011 xshf32000006 00110010000000000000000000000110 yval00005A2B 00000000000000000101101000101011 xshf00168AC0 00000000000101101000101011000000 xshf00168AC0 00000000000101101000101011000000 xshf32168AC6 00110010000101101000101011000110 yval643C9869 01100100001111001001100001101001 xval66334873 01100110001100110100100001110011 yval0643C986 00000110010000111100100110000110 xshf0003C986 00000000000000111100100110000110 xshf0001E4C3 00000000000000011110010011000011 xshf66000033 01100110000000000000000000110011 yval0001E4C3 00000000000000011110010011000011 xshf007930C0 00000000011110010011000011000000 xshf007930C0 00000000011110010011000011000000 xshf667930F3 01100110011110010011000011110011 yval74B0DC51 01110100101100001101110001010001 xval19495CFF 00011001010010010101110011111111 yval074B0DC5 00000111010010110000110111000101 xshf00030DC5 00000000000000110000110111000101 xshf000186E2 00000000000000011000011011100010 xshf1800003F 00011000000000000000000000111111 yval000186E2 00000000000000011000011011100010 xshf0061B880 00000000011000011011100010000000 xshf0061B880 00000000011000011011100010000000 xshf1861B8BF 00011000011000011011100010111111 yval2AE8944A 00101010111010001001010001001010 xval625558EC 01100010010101010101100011101100 yval02AE8944 00000010101011101000100101000100 xshf00068944 00000000000001101000100101000100 xshf000344A2 00000000000000110100010010100010 xshf6200002C 01100010000000000000000000101100 yval000344A2 00000000000000110100010010100010 xshf00D12880 00000000110100010010100010000000 xshf00D12880 00000000110100010010100010000000 xshf62D128AC 01100010110100010010100010101100 yval238E1F29 00100011100011100001111100101001 xval46E87CCD 01000110111010000111110011001101 yval0238E1F2 00000010001110001110000111110010 xshf0000E1F2 00000000000000001110000111110010 xshf000070F9 00000000000000000111000011111001 xshf4600000D 01000110000000000000000000001101 yval000070F9 00000000000000000111000011111001 xshf001C3E40 00000000000111000011111001000000 xshf001C3E40 00000000000111000011111001000000 xshf461C3E4D 01000110000111000011111001001101 yval3D1B58BA 00111101000110110101100010111010 xval507ED7AB 01010000011111101101011110101011 yval03D1B58B 00000011110100011011010110001011 xshf0001B58B 00000000000000011011010110001011 xshf0000DAC5 00000000000000001101101011000101 xshf5000002B 01010000000000000000000000101011 yval0000DAC5 00000000000000001101101011000101 xshf0036B140 00000000001101101011000101000000 xshf0036B140 00000000001101101011000101000000 xshf5036B16B 01010000001101101011000101101011 yval MIPS程序:这是为mars模拟器设置的.特别地，以十六进制打印值的syscall 34仅在mars中存在，而在spim中不存在 中.因此，要么获取火星: http://courses.missouristate.edu/KenVollmar/mars/或[使用spim]将34更改为1以十进制打印 # these work for the mars simulator .eqv XHI 22 .eqv XLO 4 .eqv YHI 24 .eqv YLO 6 # these work for the spim simulator ###XHI = 22 ###XLO = 4 ###YHI = 24 ###YLO = 6 .datatestdata: .word 0xFFFFFFFF,0x00000000,0x00FFFFC0 .word 0x00000000,0xFFFFFFFF,0xFE00003F .word 0x6B8B4567,0x327B23C6,0x32168AC6 .word 0x643C9869,0x66334873,0x667930F3 .word 0x74B0DC51,0x19495CFF,0x1861B8BF .word 0x2AE8944A,0x625558EC,0x62D128AC .word 0x238E1F29,0x46E87CCD,0x461C3E4D .word 0x3D1B58BA,0x507ED7AB,0x5036B16Bedata:msg_nl: .asciiz "\n"msg_xrmsk: .asciiz "xrmsk "msg_xlmsk: .asciiz "xlmsk "msg_yrmsk: .asciiz "yrmsk "msg_ylmsk: .asciiz "ylmsk "msg_xval: .asciiz "xval "msg_yval: .asciiz "yval "msg_pass: .asciiz "pass "msg_fail: .asciiz "FAIL "msg_ans: .asciiz "answ " .text .globl mainmain: jal setup2 la $s6,testdata la $s7,edatamain_loop: jal test addiu $s6,$s6,12 blt $s6,$s7,main_loop li $v0,10 syscall# test -- test the mergetest: subu $sp,$sp,4 sw $ra,0($sp) li $v0,4 la $a0,msg_nl syscall lw $t0,0($s6) # get source value lw $t1,4($s6) # get destination value lw $t2,8($s6) # get solution value # print the X value la $a0,msg_xval move $a1,$t0 jal print # print the Y value la $a0,msg_yval move $a1,$t1 jal print # do the operation jal merge bne $t1,$t2,test_fail la $a0,msg_pass move $a1,$t1 jal print j test_donetest_fail: la $a0,msg_fail move $a1,$t1 jal print # print the result la $a0,msg_ans move $a1,$t2 jal printtest_done: lw $ra,0($sp) addu $sp,$sp,4 jr $ra# print -- print number## arguments:# a0 -- string# a1 -- valueprint: # output the string li $v0,4 syscall li $v0,34 # syscall print hex move $a0,$a1 syscall li $v0,4 la $a0,msg_nl syscall jr $ra# merge -- merge the data## arguments:# t0 -- source value# t1 -- target value## registers:# t7 -- xshf# t6 -- ~ylmskmerge: srl $t7,$t0,XLO # E1: xshf = xval >> xlo and $t7,$t7,$s0 # E2: xshf &= xrmsk srl $t7,$t7,1 # E3: xshf >>= 1 not $t6,$s3 # M1: get ~ylmsk and $t1,$t1,$t6 # M1: yval &= ~ylmsk sll $t7,$t7,YLO # M2: xshf <<= ylo and $t7,$t7,$s3 # M2: xshf &= ylmsk or $t1,$t1,$t7 # M3: yval |= xshf jr $ra # return# setup2 -- set up the mask values## RETURNS:# s0 -- xrmsk# s1 -- xlmsk# s2 -- yrmsk# s3 -- ylmsk## registers:# a0 -- hi bit value# a1 -- lo bit valuesetup2: subu $sp,$sp,4 sw $ra,0($sp) # set up the xval masks li $a0,XHI li $a1,XLO jal setup1 move $s0,$v0 move $s1,$v1 la $a0,msg_xrmsk move $a1,$s0 jal print la $a0,msg_xlmsk move $a1,$s1 jal print # set up the yval masks li $a0,YHI li $a1,YLO jal setup1 move $s2,$v0 move $s3,$v1 la $a0,msg_yrmsk move $a1,$s2 jal print la $a0,msg_ylmsk move $a1,$s3 jal print lw $ra,0($sp) addu $sp,$sp,4 jr $ra # return# setup1 -- set up the mask values## RETURNS:# v0 -- rmsk# v1 -- lmsk## arguments:# a0 -- hi bit value# a1 -- lo bit value## registers:# t0 -- wid# t1 -- 32 - widsetup1: sub $t0,$a0,$a1 # wid = hi - lo addi $t0,$t0,1 # wid += 1 li $v0,0xFFFFFFFF # rmsk = 0xFFFFFFFF # get 32 - wid li $t1,32 sub $t1,$t1,$t0 srlv $v0,$v0,$t1 # rmsk >>= (32 - wid) sllv $v1,$v0,$a1 # lmsk = rmsk << lo jr $ra # returnI need to extract the value in bits 22 down to 4 from register $t0, compute the half of this value (assumed unsigned integer), and use the new value to replace bits 24 down to 6 in register $t1 without changing the others bits in $t1. The value isn't given but I don't think that should be an issue. There are 32 bits per registerI'm a bit new to MIPs so I'm not sure how to go about solving this problem 解决方案 I've broken down the invidual steps of the algorithm. I then created a C prototype/test program. And, finally, I created a mips asm program.Those are the steps I would recommend for you [or anybody else], particularly when getting started.Writing the code in C first [or at least prototyping it in C-like pseudo code], makes debugging of the algorithm easier.From the C program, I was able to create test data for the mips program. The test data includes the solution that the C program got.The mips program would treat this as a pass/fail diagnostic. This might seem like overkill, but in the first version of the asm program, there was a bug. I had used a wrong register in the srlv instruction's third argument and the diagnostic actually failed the tests (e.g. I used $t0 instead of $t1).Terminology:This is the matchup of the terms:xval: $t0xhi: 22xlo: 4yval: $t1yhi: 24ylo: 6Extract step (1):Given a value xval, whenever you see "extract bits xhi to xlo", the first thing to do is right shift xval by xlo:xshf = xval >> xloBut now, xshf still has the bits that were to the left of xhi, so we need to mask them.Formulas:The bit width of an "inclusive" bit range is:wid = (hi - lo) + 1So, the "right justified" mask is:rmsk = (0xFFFFFFFF >> (32 - wid))The "left justified" mask is:lmsk = (rmsk << lo)Note: The above equations work dynamically [as above]. Or, if we have fixed numbers, we can calculate the final values by hand to produce constants.Extract step (2):So, to get the isolated value for the bit range, we now apply the mask:xshf &= xrmskThis is the first part of the problem. We've isolated the necessary bits, so they are now in the rightmost bits of xshf (i.e. bits (xwid-1) to 0).Extract step (3):The above was for general bit extraction. The specific problem requires that we divide by 2:xshf >>= 1Merge step (1):The second part of the problem is that we have to apply the xshf to the target value yval.yval has a different range: yhi to ylo. We apply the formulas to get the appropriate values for yval.We must clear out the old bits in yval:yval &= ~ylmskMerge step (2):We need to do two things to xshf:"clean up" xshf so that only the correct bits in yval get modifiedShift xshf into the correct position for merging with yvalWe can accomplish this in one of two ways. The following two sequences are equivalent:xshf &= yrmskxshf <<= yloOr:xshf <<= yloxshf &= ylmskNote: Because the bit widths in the specific problem are the same, the masking step can be eliminated (i.e. xshf had already been masked by xrmsk and it is the same as yrmsk. So, either masking step is not required).Merge step (3):Now, we merge in the shifted value:yval |= xshfThat's it--we're done ...Prototype:Here's some C code that combines all this.Because the bit range values are fixed, the mask values are precalculated once. If they had to vary, the mask code would have to recalculate them on each merge call.Also note that the masks are constants because the ranges are fixed.#include <stdio.h>#include <stdlib.h>int opt_v;typedef unsigned int u32;u32 xval;#define XHI 22#define XLO 4u32 yval;#define YHI 24#define YLO 6u32 xrmsk;u32 xlmsk;u32 yrmsk;u32 ylmsk;#define WID(_hi,_lo) (((_hi) - (_lo)) + 1)#define RMSK(_hi,_lo) (0xFFFFFFFF >> (32 - WID(_hi,_lo)))#define LMSK(_hi,_lo) (RMSK(_hi,_lo) << (_lo))#define SHOW(_sym) \ show(_sym,#_sym)#define SHOWX(_sym) \ if (opt_v) \ SHOW(_sym)voidshow(u32 val,const char *sym){ u32 bitmsk; u32 bitval; printf("%8.8X ",val); for (bitmsk = 1u << 31; bitmsk != 0; bitmsk >>= 1) { bitval = val & bitmsk; printf("%d",bitval ? 1 : 0); } printf(" %s\n",sym);}voidmerge(void){ u32 xshf; SHOW(xval); SHOW(yval); // extract (1): xshf = xval >> XLO; SHOW(xshf); // extract (2): SHOWX(xrmsk); xshf &= xrmsk; SHOW(xshf); // extract (3): xshf >>= 1; SHOW(xshf); // merge (1): SHOWX(yrmsk); SHOWX(ylmsk); yval &= ~ylmsk; SHOW(yval); // merge (2): xshf &= yrmsk; // belt and ... SHOW(xshf); xshf <<= YLO; SHOW(xshf); xshf &= ylmsk; // ... suspenders SHOW(xshf); // merge (3) yval |= xshf; SHOW(yval);}voidtest(u32 y,u32 x){ printf("\n"); yval = y; xval = x; merge();}// main -- main programintmain(int argc,char **argv){ char *cp; --argc; ++argv; for (; argc > 0; --argc, ++argv) { cp = *argv; if (*cp != '-') break; switch (cp[1]) { case 'v': opt_v = ! opt_v; break; default: break; } } xrmsk = RMSK(XHI,XLO); SHOW(xrmsk); xlmsk = LMSK(XHI,XLO); SHOW(xlmsk); yrmsk = RMSK(YHI,YLO); SHOW(yrmsk); ylmsk = LMSK(YHI,YLO); SHOW(ylmsk); test(0,~0); test(~0,0); for (int idx = 0; idx <= 5; ++idx) test(rand(),rand()); return 0;}Output:0007FFFF 00000000000001111111111111111111 xrmsk007FFFF0 00000000011111111111111111110000 xlmsk0007FFFF 00000000000001111111111111111111 yrmsk01FFFFC0 00000001111111111111111111000000 ylmskFFFFFFFF 11111111111111111111111111111111 xval00000000 00000000000000000000000000000000 yval0FFFFFFF 00001111111111111111111111111111 xshf0007FFFF 00000000000001111111111111111111 xshf0003FFFF 00000000000000111111111111111111 xshf00000000 00000000000000000000000000000000 yval0003FFFF 00000000000000111111111111111111 xshf00FFFFC0 00000000111111111111111111000000 xshf00FFFFC0 00000000111111111111111111000000 xshf00FFFFC0 00000000111111111111111111000000 yval00000000 00000000000000000000000000000000 xvalFFFFFFFF 11111111111111111111111111111111 yval00000000 00000000000000000000000000000000 xshf00000000 00000000000000000000000000000000 xshf00000000 00000000000000000000000000000000 xshfFE00003F 11111110000000000000000000111111 yval00000000 00000000000000000000000000000000 xshf00000000 00000000000000000000000000000000 xshf00000000 00000000000000000000000000000000 xshfFE00003F 11111110000000000000000000111111 yval6B8B4567 01101011100010110100010101100111 xval327B23C6 00110010011110110010001111000110 yval06B8B456 00000110101110001011010001010110 xshf0000B456 00000000000000001011010001010110 xshf00005A2B 00000000000000000101101000101011 xshf32000006 00110010000000000000000000000110 yval00005A2B 00000000000000000101101000101011 xshf00168AC0 00000000000101101000101011000000 xshf00168AC0 00000000000101101000101011000000 xshf32168AC6 00110010000101101000101011000110 yval643C9869 01100100001111001001100001101001 xval66334873 01100110001100110100100001110011 yval0643C986 00000110010000111100100110000110 xshf0003C986 00000000000000111100100110000110 xshf0001E4C3 00000000000000011110010011000011 xshf66000033 01100110000000000000000000110011 yval0001E4C3 00000000000000011110010011000011 xshf007930C0 00000000011110010011000011000000 xshf007930C0 00000000011110010011000011000000 xshf667930F3 01100110011110010011000011110011 yval74B0DC51 01110100101100001101110001010001 xval19495CFF 00011001010010010101110011111111 yval074B0DC5 00000111010010110000110111000101 xshf00030DC5 00000000000000110000110111000101 xshf000186E2 00000000000000011000011011100010 xshf1800003F 00011000000000000000000000111111 yval000186E2 00000000000000011000011011100010 xshf0061B880 00000000011000011011100010000000 xshf0061B880 00000000011000011011100010000000 xshf1861B8BF 00011000011000011011100010111111 yval2AE8944A 00101010111010001001010001001010 xval625558EC 01100010010101010101100011101100 yval02AE8944 00000010101011101000100101000100 xshf00068944 00000000000001101000100101000100 xshf000344A2 00000000000000110100010010100010 xshf6200002C 01100010000000000000000000101100 yval000344A2 00000000000000110100010010100010 xshf00D12880 00000000110100010010100010000000 xshf00D12880 00000000110100010010100010000000 xshf62D128AC 01100010110100010010100010101100 yval238E1F29 00100011100011100001111100101001 xval46E87CCD 01000110111010000111110011001101 yval0238E1F2 00000010001110001110000111110010 xshf0000E1F2 00000000000000001110000111110010 xshf000070F9 00000000000000000111000011111001 xshf4600000D 01000110000000000000000000001101 yval000070F9 00000000000000000111000011111001 xshf001C3E40 00000000000111000011111001000000 xshf001C3E40 00000000000111000011111001000000 xshf461C3E4D 01000110000111000011111001001101 yval3D1B58BA 00111101000110110101100010111010 xval507ED7AB 01010000011111101101011110101011 yval03D1B58B 00000011110100011011010110001011 xshf0001B58B 00000000000000011011010110001011 xshf0000DAC5 00000000000000001101101011000101 xshf5000002B 01010000000000000000000000101011 yval0000DAC5 00000000000000001101101011000101 xshf0036B140 00000000001101101011000101000000 xshf0036B140 00000000001101101011000101000000 xshf5036B16B 01010000001101101011000101101011 yvalMIPS program:This is set up for the mars simulator. In particular, the syscall 34 to print a value in hex only exists in mars and not in spim. So, either get mars: http://courses.missouristate.edu/KenVollmar/mars/ or [using spim] change the 34 to 1 to print in decimal # these work for the mars simulator .eqv XHI 22 .eqv XLO 4 .eqv YHI 24 .eqv YLO 6 # these work for the spim simulator ###XHI = 22 ###XLO = 4 ###YHI = 24 ###YLO = 6 .datatestdata: .word 0xFFFFFFFF,0x00000000,0x00FFFFC0 .word 0x00000000,0xFFFFFFFF,0xFE00003F .word 0x6B8B4567,0x327B23C6,0x32168AC6 .word 0x643C9869,0x66334873,0x667930F3 .word 0x74B0DC51,0x19495CFF,0x1861B8BF .word 0x2AE8944A,0x625558EC,0x62D128AC .word 0x238E1F29,0x46E87CCD,0x461C3E4D .word 0x3D1B58BA,0x507ED7AB,0x5036B16Bedata:msg_nl: .asciiz "\n"msg_xrmsk: .asciiz "xrmsk "msg_xlmsk: .asciiz "xlmsk "msg_yrmsk: .asciiz "yrmsk "msg_ylmsk: .asciiz "ylmsk "msg_xval: .asciiz "xval "msg_yval: .asciiz "yval "msg_pass: .asciiz "pass "msg_fail: .asciiz "FAIL "msg_ans: .asciiz "answ " .text .globl mainmain: jal setup2 la $s6,testdata la $s7,edatamain_loop: jal test addiu $s6,$s6,12 blt $s6,$s7,main_loop li $v0,10 syscall# test -- test the mergetest: subu $sp,$sp,4 sw $ra,0($sp) li $v0,4 la $a0,msg_nl syscall lw $t0,0($s6) # get source value lw $t1,4($s6) # get destination value lw $t2,8($s6) # get solution value # print the X value la $a0,msg_xval move $a1,$t0 jal print # print the Y value la $a0,msg_yval move $a1,$t1 jal print # do the operation jal merge bne $t1,$t2,test_fail la $a0,msg_pass move $a1,$t1 jal print j test_donetest_fail: la $a0,msg_fail move $a1,$t1 jal print # print the result la $a0,msg_ans move $a1,$t2 jal printtest_done: lw $ra,0($sp) addu $sp,$sp,4 jr $ra# print -- print number## arguments:# a0 -- string# a1 -- valueprint: # output the string li $v0,4 syscall li $v0,34 # syscall print hex move $a0,$a1 syscall li $v0,4 la $a0,msg_nl syscall jr $ra# merge -- merge the data## arguments:# t0 -- source value# t1 -- target value## registers:# t7 -- xshf# t6 -- ~ylmskmerge: srl $t7,$t0,XLO # E1: xshf = xval >> xlo and $t7,$t7,$s0 # E2: xshf &= xrmsk srl $t7,$t7,1 # E3: xshf >>= 1 not $t6,$s3 # M1: get ~ylmsk and $t1,$t1,$t6 # M1: yval &= ~ylmsk sll $t7,$t7,YLO # M2: xshf <<= ylo and $t7,$t7,$s3 # M2: xshf &= ylmsk or $t1,$t1,$t7 # M3: yval |= xshf jr $ra # return# setup2 -- set up the mask values## RETURNS:# s0 -- xrmsk# s1 -- xlmsk# s2 -- yrmsk# s3 -- ylmsk## registers:# a0 -- hi bit value# a1 -- lo bit valuesetup2: subu $sp,$sp,4 sw $ra,0($sp) # set up the xval masks li $a0,XHI li $a1,XLO jal setup1 move $s0,$v0 move $s1,$v1 la $a0,msg_xrmsk move $a1,$s0 jal print la $a0,msg_xlmsk move $a1,$s1 jal print # set up the yval masks li $a0,YHI li $a1,YLO jal setup1 move $s2,$v0 move $s3,$v1 la $a0,msg_yrmsk move $a1,$s2 jal print la $a0,msg_ylmsk move $a1,$s3 jal print lw $ra,0($sp) addu $sp,$sp,4 jr $ra # return# setup1 -- set up the mask values## RETURNS:# v0 -- rmsk# v1 -- lmsk## arguments:# a0 -- hi bit value# a1 -- lo bit value## registers:# t0 -- wid# t1 -- 32 - widsetup1: sub $t0,$a0,$a1 # wid = hi - lo addi $t0,$t0,1 # wid += 1 li $v0,0xFFFFFFFF # rmsk = 0xFFFFFFFF # get 32 - wid li $t1,32 sub $t1,$t1,$t0 srlv $v0,$v0,$t1 # rmsk >>= (32 - wid) sllv $v1,$v0,$a1 # lmsk = rmsk << lo jr $ra # return 这篇关于如何从寄存器中提取位中的值，并用它们替换其他寄存器中的位? (MIP汇编语言)的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！ 上岸，阿里云！