Use the same bias, then an arithmetic right shift by ten:
div1024:
    asrs r3, r0, #31    // -1 when a<0, otherwise 0
    lsrs r3, r3, #22    // b = 1023 when a<0, otherwise 0
    adds r0, r0, r3     // a+b, representable for every signed input
    asrs r0, r0, #10    // floor((a+b)/1024)
    bx lr
An arithmetic right shift of a two's complement integer computes division rounded down. For , this already equals truncation towards zero. For , the signed power-of-two division by biasing identity is
(1)
Indeed, writing with makes the adjusted numerator ; its quotient rounded down is for every , including zero. Thus the code returns the signed quotient in all cases and contains no data-dependent branch. The final bx lr simply returns to the caller.

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