1/* libs/opengles/fixed_asm.S 2** 3** Copyright 2006, The Android Open Source Project 4** 5** Licensed under the Apache License, Version 2.0 (the "License"); 6** you may not use this file except in compliance with the License. 7** You may obtain a copy of the License at 8** 9** http://www.apache.org/licenses/LICENSE-2.0 10** 11** Unless required by applicable law or agreed to in writing, software 12** distributed under the License is distributed on an "AS IS" BASIS, 13** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14** See the License for the specific language governing permissions and 15** limitations under the License. 16*/ 17 18 19 .text 20 .align 2 21 22 .global gglFloatToFixed 23 .type gglFloatToFixed, %function 24 .global gglFloatToFixedFast 25 .type gglFloatToFixedFast, %function 26 27 28/* 29 * Converts a float to a s15.16 fixed-point number. 30 * this doesn't handle floats out of the [-32768, +32768[ range 31 * and doesn't performs round-to-nearest. 32 * however, it's very fast :-) 33 */ 34 35gglFloatToFixedFast: 36 movs r1, r0, lsl #1 /* remove bit sign */ 37 mov r2, #0x8E /* 127 + 15 */ 38 sub r1, r2, r1, lsr #24 /* compute shift */ 39 mov r2, r0, lsl #8 /* mantissa<<8 */ 40 orr r2, r2, #0x80000000 /* add the missing 1 */ 41 mov r0, r2, lsr r1 /* scale to 16.16 */ 42 rsbcs r0, r0, #0 /* negate if needed */ 43 bx lr 44 45/* 46 * this version rounds-to-nearest and saturates numbers 47 * outside the range (but not NaNs). 48 */ 49 50gglFloatToFixed: 51 mov r1, r0, lsl #1 /* remove bit sign */ 52 mov r2, #0x8E /* 127 + 15 */ 53 subs r1, r2, r1, lsr #24 /* compute shift */ 54 bls 0f /* too big */ 55 mov r2, r0, lsl #8 /* mantissa<<8 */ 56 orr r2, r2, #0x80000000 /* add the missing 1 */ 57 mov r3, r0 58 movs r0, r2, lsr r1 /* scale to 16.16 */ 59 addcs r0, r0, #1 /* round-to-nearest */ 60 tst r3, #0x80000000 /* negative? */ 61 rsbne r0, r0, #0 /* negate if needed */ 62 bx lr 63 640: ands r0, r0, #0x80000000 /* keep only the sign bit */ 65 moveq r0, #0x7fffffff /* positive, maximum value */ 66 bx lr 67 68