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| 1 | section .data | |
| 2 | ||
| 3 | section .bss | |
| 4 | ||
| 5 | section .text | |
| 6 | ||
| 7 | global test_distance ; makes function visible from extern | |
| 8 | ||
| 9 | x1 equ 4 ; pointer a float x1, needs 32 bit (4 bytes) | |
| 10 | x2 equ 8 ; puntatore a float x2, needs 32 bit (4 bytes) | |
| 11 | d equ 12 ; int 32 bit, dimension of vectors | |
| 12 | ||
| 13 | test_distance: | |
| 14 | - | mov ecx, [esp+x1] ; ESI = address of vector x1 |
| 14 | + | mov ecx, [esp+x1] ; ECX = address of vector x1 |
| 15 | - | mov edx, [esp+x2] ; EDI = address of vector x2 |
| 15 | + | mov edx, [esp+x2] ; EDX = address of vector x2 |
| 16 | - | mov eax, [esp+d] ; EBX = Number of elements in vectors |
| 16 | + | mov eax, [esp+d] ; EAX = Number of elements in vectors |
| 17 | ||
| 18 | ; Traverse vectors in reverse order | |
| 19 | fldz ; Load zero on top of stack (sum starts at zero) | |
| 20 | ||
| 21 | ; Sum the square of differences | |
| 22 | nextvec: | |
| 23 | ; Load the current vector elements | |
| 24 | fld dword [ecx+eax*4-4] | |
| 25 | fld dword [edx+eax*4-4] | |
| 26 | fsubp ; Find the difference | |
| 27 | fmul st0 ; Square the value | |
| 28 | faddp ; Add it to the current sum | |
| 29 | dec eax ; Go to previous element in the array | |
| 30 | jnz nextvec ; If EBX is zero we are finished | |
| 31 | ||
| 32 | fsqrt ; Distance = sqrt of sum of the square of the differences | |
| 33 | ; Distance is at the top of the stack in ST0 | |
| 34 | ; Functions returning a float place the result in ST0 | |
| 35 | ; to the caller | |
| 36 | ||
| 37 | ret |
