Bryan Cisneros / Mbed 2 deprecated VortexFlowmeter_Project1

project1

Dependencies:   mbed TSI MMA8451Q

rootsquare.c@2:316ddc3b4384, 2019-09-19 (annotated)

Committer:
bcis93
Date:
Thu Sep 19 20:45:17 2019 +0000
Revision:
2:316ddc3b4384
Parent:
1:69b15daf7a7d 
Adding dimming with the touch sensor (using the TSI library)

Who changed what in which revision?

UserRevisionLine numberNew contents of line
nmaududi 0:529f900ad93b 1 /************************************************************************//**
nmaududi 0:529f900ad93b 2 * \file main.c
nmaududi 0:529f900ad93b 3 * \brief LAB EXERCISE 5.2 - SQUARE ROOT APPROXIMATION
nmaududi 0:529f900ad93b 4 *
nmaududi 0:529f900ad93b 5 * Write an assembly code subroutine to approximate the square root of an
nmaududi 0:529f900ad93b 6 * argument using the bisection method. All math is done with integers, so the
nmaududi 0:529f900ad93b 7 * resulting square root will also be an integer
nmaududi 0:529f900ad93b 8 ******************************************************************************
nmaududi 0:529f900ad93b 9 * GOOD LUCK!
nmaududi 0:529f900ad93b 10 ****************************************************************************/
nmaududi 0:529f900ad93b 11
nmaududi 0:529f900ad93b 12 #include "stdint.h"
bcis93 1:69b15daf7a7d 13 #include <stdio.h>
nmaududi 0:529f900ad93b 14
nmaududi 0:529f900ad93b 15
nmaududi 0:529f900ad93b 16 /** @cond DO_NOT_INCLUDE_WITH_DOXYGEN */
nmaududi 0:529f900ad93b 17 #include "string.h"
nmaududi 0:529f900ad93b 18 /** @endcond */
nmaududi 0:529f900ad93b 19
nmaududi 0:529f900ad93b 20 /**
nmaududi 0:529f900ad93b 21 * @brief 5863 Write a brief description of the function here
nmaududi 0:529f900ad93b 22 *
nmaududi 0:529f900ad93b 23 * Detailed description of the function after one line gap
nmaududi 0:529f900ad93b 24 *
nmaududi 0:529f900ad93b 25 * @note You can also add a note this way
nmaududi 0:529f900ad93b 26 *
nmaududi 0:529f900ad93b 27 * @param[in]
nmaududi 0:529f900ad93b 28 * You can also start writing on a new line.
nmaududi 0:529f900ad93b 29 * And continue on the next line. This is how you describe an input parameter
nmaududi 0:529f900ad93b 30 *
nmaududi 0:529f900ad93b 31 * @return
nmaududi 0:529f900ad93b 32 * This is how you describe the return value
nmaududi 0:529f900ad93b 33 *
nmaududi 0:529f900ad93b 34 */
nmaududi 0:529f900ad93b 35 __asm int my_sqrt(int x){
bcis93 1:69b15daf7a7d 36 PUSH {r4-r7} ; we use r4-r7, which are callee stored registers, so we need to save them on the stack
nmaududi 0:529f900ad93b 37
bcis93 1:69b15daf7a7d 38 MOVS r1, #0; r1 will be the register to store a, initialized to 0
bcis93 1:69b15daf7a7d 39 MOVS r2,#200; r2 is for variable b, store the largest squaure root round[sqrt(2^31-1)] (46341)
bcis93 1:69b15daf7a7d 40 MOVS r3,#1; r3 is for variable c, it has been define and intialized
nmaududi 0:529f900ad93b 41 NEGS r3,r3;
bcis93 1:69b15daf7a7d 42 MOVS r4,#0; r4 is for variable done
nmaududi 0:529f900ad93b 43
nmaududi 0:529f900ad93b 44 loop_while
nmaududi 0:529f900ad93b 45
bcis93 1:69b15daf7a7d 46 MOVS r5,r3; r5 is allocated for c old within the code
bcis93 1:69b15daf7a7d 47 ADDS r3, r1, r2; stores into c = a+b
bcis93 1:69b15daf7a7d 48 LSRS r3,r3,#1; multiply c by 0.5 to get c= (a+b)/2, completed a shift to complete division
nmaududi 0:529f900ad93b 49 MOVS r6,r3; r6 is allocated for c within the code
bcis93 1:69b15daf7a7d 50 MULS r6,r6,r6; r6 now contains x*x as implemented int code
nmaududi 0:529f900ad93b 51
bcis93 1:69b15daf7a7d 52 CMP r6,r0; Compare c*c and x, start of the if loop
bcis93 1:69b15daf7a7d 53 BEQ sqrt_loop_done
bcis93 1:69b15daf7a7d 54 BLT sqrt_elseif
nmaududi 0:529f900ad93b 55
nmaududi 0:529f900ad93b 56 MOVS r2,r3; b is loaded with the value of c, b <--c
nmaududi 0:529f900ad93b 57
bcis93 1:69b15daf7a7d 58 B end_of_sqrtloop
nmaududi 0:529f900ad93b 59 sqrt_elseif
nmaududi 0:529f900ad93b 60 MOVS r1,r3; a is loaded with the value of c, a <--c
bcis93 1:69b15daf7a7d 61 B end_of_sqrtloop
nmaududi 0:529f900ad93b 62
nmaududi 0:529f900ad93b 63 sqrt_loop_done
nmaududi 0:529f900ad93b 64
bcis93 1:69b15daf7a7d 65 MOVS r4,#1; store 1 into the variable done
nmaududi 0:529f900ad93b 66
nmaududi 0:529f900ad93b 67 end_of_sqrtloop
bcis93 1:69b15daf7a7d 68 MVNS r6,r4; r6 ==!done, was c*c above
bcis93 1:69b15daf7a7d 69 CMP r5, r3; compare cold and c
bcis93 1:69b15daf7a7d 70 BNE skip
bcis93 1:69b15daf7a7d 71 MOVS r7,#0; set r7 equal to 0 if cold and c are equal
bcis93 1:69b15daf7a7d 72 B skip_over
nmaududi 0:529f900ad93b 73 skip
bcis93 1:69b15daf7a7d 74 MOVS r7,#1;
bcis93 1:69b15daf7a7d 75 NEGS r7,r7;
nmaududi 0:529f900ad93b 76 skip_over
bcis93 1:69b15daf7a7d 77 CMP r6,r7;
bcis93 1:69b15daf7a7d 78 BEQ loop_while
bcis93 1:69b15daf7a7d 79
bcis93 1:69b15daf7a7d 80 MOVS r0,r3 ; store the return value in r0
bcis93 1:69b15daf7a7d 81 POP {r4-r7} ; restore r4-r7
bcis93 1:69b15daf7a7d 82 BLX lr ; Else return from subroutine with link and returning the variable c
nmaududi 0:529f900ad93b 83 //CMP
nmaududi 0:529f900ad93b 84
nmaududi 0:529f900ad93b 85
nmaududi 0:529f900ad93b 86 }
nmaududi 0:529f900ad93b 87
nmaududi 0:529f900ad93b 88 /*----------------------------------------------------------------------------
nmaududi 0:529f900ad93b 89 MAIN function
nmaududi 0:529f900ad93b 90 *----------------------------------------------------------------------------*/
nmaududi 0:529f900ad93b 91 /**
nmaududi 0:529f900ad93b 92 * @brief Main function
nmaududi 0:529f900ad93b 93 *
nmaududi 0:529f900ad93b 94 * Detailed description of the main
nmaududi 0:529f900ad93b 95 */
bcis93 2:316ddc3b4384 96 /*
nmaududi 0:529f900ad93b 97 int main(void){
bcis93 1:69b15daf7a7d 98 int test_values[4] = {2,4,22,121};
bcis93 1:69b15daf7a7d 99 volatile int result = 0;
bcis93 1:69b15daf7a7d 100
bcis93 1:69b15daf7a7d 101 for (int i = 0; i < 4; i++)
bcis93 1:69b15daf7a7d 102 {
bcis93 1:69b15daf7a7d 103 result = my_sqrt(test_values[i]);
bcis93 1:69b15daf7a7d 104 printf("my_sqrt(%d): %d\n\r", test_values[i], result);
bcis93 1:69b15daf7a7d 105 }
nmaududi 0:529f900ad93b 106 }
bcis93 2:316ddc3b4384 107 */
nmaududi 0:529f900ad93b 108
nmaududi 0:529f900ad93b 109 // *******************************ARM University Program Copyright © ARM Ltd 2014*************************************/