1 @ Written by Wilco Dijkstra, 1996. 2 @ Refer to NOTICE file at the root of git project. 3 @ 4 @ Minor modifications in code style for WebRTC, 2012. 5 @ Output is bit-exact with the reference C code in spl_sqrt_floor.c. 6 7 @ Input : r0 32 bit unsigned integer 8 @ Output: r0 = INT (SQRT (r0)), precision is 16 bits 9 @ Registers touched: r1, r2 10 11 .global WebRtcSpl_SqrtFloor 12 13 .align 2 14 WebRtcSpl_SqrtFloor: 15 .fnstart 16 mov r1, #3 << 30 17 mov r2, #1 << 30 18 19 @ unroll for i = 0 .. 15 20 21 cmp r0, r2, ror #2 * 0 22 subhs r0, r0, r2, ror #2 * 0 23 adc r2, r1, r2, lsl #1 24 25 cmp r0, r2, ror #2 * 1 26 subhs r0, r0, r2, ror #2 * 1 27 adc r2, r1, r2, lsl #1 28 29 cmp r0, r2, ror #2 * 2 30 subhs r0, r0, r2, ror #2 * 2 31 adc r2, r1, r2, lsl #1 32 33 cmp r0, r2, ror #2 * 3 34 subhs r0, r0, r2, ror #2 * 3 35 adc r2, r1, r2, lsl #1 36 37 cmp r0, r2, ror #2 * 4 38 subhs r0, r0, r2, ror #2 * 4 39 adc r2, r1, r2, lsl #1 40 41 cmp r0, r2, ror #2 * 5 42 subhs r0, r0, r2, ror #2 * 5 43 adc r2, r1, r2, lsl #1 44 45 cmp r0, r2, ror #2 * 6 46 subhs r0, r0, r2, ror #2 * 6 47 adc r2, r1, r2, lsl #1 48 49 cmp r0, r2, ror #2 * 7 50 subhs r0, r0, r2, ror #2 * 7 51 adc r2, r1, r2, lsl #1 52 53 cmp r0, r2, ror #2 * 8 54 subhs r0, r0, r2, ror #2 * 8 55 adc r2, r1, r2, lsl #1 56 57 cmp r0, r2, ror #2 * 9 58 subhs r0, r0, r2, ror #2 * 9 59 adc r2, r1, r2, lsl #1 60 61 cmp r0, r2, ror #2 * 10 62 subhs r0, r0, r2, ror #2 * 10 63 adc r2, r1, r2, lsl #1 64 65 cmp r0, r2, ror #2 * 11 66 subhs r0, r0, r2, ror #2 * 11 67 adc r2, r1, r2, lsl #1 68 69 cmp r0, r2, ror #2 * 12 70 subhs r0, r0, r2, ror #2 * 12 71 adc r2, r1, r2, lsl #1 72 73 cmp r0, r2, ror #2 * 13 74 subhs r0, r0, r2, ror #2 * 13 75 adc r2, r1, r2, lsl #1 76 77 cmp r0, r2, ror #2 * 14 78 subhs r0, r0, r2, ror #2 * 14 79 adc r2, r1, r2, lsl #1 80 81 cmp r0, r2, ror #2 * 15 82 subhs r0, r0, r2, ror #2 * 15 83 adc r2, r1, r2, lsl #1 84 85 bic r0, r2, #3 << 30 @ for rounding add: cmp r0, r2 adc r2, #1 86 bx lr 87 88 .fnend 89
