dest[0] = dest[0] - source[0] dest[1] = dest[1] - source[1] dest[2] = dest[2] - source[2] dest[3] = dest[3] - source[3]
The subps instruction subtracts the 4 source values (second operand) from the 4 values of the destination (an XMM register). The source can be an XMM register or a 32 bit memory location. There is also vsubps on CPUs with AVX instructions which allows using 3 XMM registers or 2 XMM registers and a memory location which can simplify coding and which subtracts 8 pairs of values.
subps xmm0, xmm1 ; subtract 4 pairs of values of xmm1 from xmm0 ; leave the rest of ymm0 as is subps xmm0, [x] ; subtract 4 pairs of values of x from xmm0 ; x is an array of floats ; leave the rest of ymm0 as is subps xmm0, [x+4*rax] ; subtract 4 pairs of values of x from xmm0 ; x is an array of floats ; rax holds the index of the first element ; leave the rest of ymm0 as is vsubps xmm3, xmm0, xmm15 ; subtract 4 pairs of values from xmm0 & xmm15 ; store results in xmm3 vsubps ymm3, ymm0, [x] ; subtract 8 pairs of values from ymm0 & x ; store results in ymm3 vsubps ymm3, ymm0, [rsi] ; subtract 8 pairs of values from ymm0 & [rsi] ; rsi contains the address of an array ; store results in ymm3