[英]Program received signal SIGSEGV, Segmentation fault using SHRD in ASM
我正在尝试将eax右移2,目前是0x037f,我想将其设置为0x0003。
我正在使用Cygwin,它可以正常编译,但是当我用gdb打开它时,一旦进入第7行,就会出现标题错误。
我试过将语法更改为(%eax,2,0)(我想将其左移2并用0填充)我也尝试过使用2,它的值为8,因为我不知道如果按字节或位移动。
asm(" push %%eax \n"
" push %%ebx \n"
" push %[nIn] \n"
" fstcw %[trueCWIn] \n" //store FPU CW into trueCW
" mov %[trueCWOut], %%eax \n" //store old FPU CW into tempVar
" mov %%eax, %[tempVarIn] \n" //store old FPU CW into tempVar
" shrd %%eax,8 \n" //shift FPU CW right to bytes
" add %[roundModeOut], %%eax \n" //adding rounding modifier
//shift left 2 bytes
//add in restore mask (0x007F)
" frndint \n" //do rounding calculation
//store result into n
" fldcw %[trueCWIn] \n" //restoring the FPU CW to normal
" pop %%ebx \n"
" pop %%eax \n"
: [trueCWOut] "=m" (trueCW),
[tempCWOut] "=m" (tempCW),
[maskOut] "=m" (mask),
[tempVarOut] "=m" (tempVar),
[roundModeOut] "=m" (roundMode),
[nOut] "=m" (n)
: [trueCWIn] "m" (trueCW),
[tempCWIn] "m" (tempCW),
[maskIn] "m" (mask),
[tempVarIn] "m" (tempVar),
[roundModeIn] "m" (roundMode),
[nIn] "m" (n)
:"eax", "ebx"
);
我找到了答案,这是一个简单的语法问题。
shr $8, %%eax
以前,eax是0x037F。 这将eax移位了8位,然后使其变为0x0003。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.