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Module 1 ECEN 5803 Project 1 Submitted by 1. Rahul Yamasani 2. Srivishnuj Alvakonda
main.cpp
- Committer:
- sral4054
- Date:
- 2017-10-12
- Revision:
- 0:a7b003d6eac1
File content as of revision 0:a7b003d6eac1:
#include "mbed.h" Serial pc(USBTX, USBRX); //serial channel over HDK USB interface Timer timer; /************************************************************************//** * \file main.c * \brief LAB EXERCISE 5.2 - SQUARE ROOT APPROXIMATION * * Write an assembly code subroutine to approximate the square root of an * argument using the bisection method. All math is done with integers, so the * resulting square root will also be an integer ****************************************************************************** * GOOD LUCK! ****************************************************************************/ #include "stdint.h" /** @cond DO_NOT_INCLUDE_WITH_DOXYGEN */ #include "string.h" /** @endcond */ /** * @brief 5863 Write a brief description of the function here * * Detailed description of the function after one line gap * * @note You can also add a note this way * * @param[in] * You can also start writing on a new line. * And continue on the next line. This is how you describe an input parameter * * @return * This is how you describe the return value * */ __asm int my_sqrt(int x){ PUSH {R4-R7} ; LDR R1, =0 ;done = 0 LDR R7, =0 ;a=0 LDR R2, =0xFFFF ;b=2^31 -1 LDR R3, =0xFFFFFFFF ;c=-1 DO_WHILE MOV R4, R3 ;c_old = c HERE R4 is being considered as c_old ADDS R5, R2, R7 ;R5 = a+b ASRS R5, R5, #1 ;R5 >> 1 which is nothing but (a+b/2) MOV R3, R5 ;c = (a+b)/2 MOV R6,R3 MULS R6, R3, R6 ;R6 = c*c CMP R6,R0 ;compare c*c and x (input integer) BEQ DONE BLT LESS_THAN MOV R2, R3 ;setting b=c B FINAL LESS_THAN MOV R7,R3 ;setting a=c B FINAL DONE LDR R1, =1 ;setting done = 1 B FINAL ;return C FINAL CMP R1, #1 ;compare done = 1 BEQ END BNE COMPARE COMPARE CMP R4, R3 ;compare c_old and c BNE DO_WHILE BEQ END END MOV R0, R3 POP {R4-R7} BX LR } void printCpuCycles(double readValue, int number, int sqrt) { double cpuCycles = 0; cpuCycles = (readValue * 48000000); // read value * frequqncy of clock pc.printf("Sqrt of %d using bisection menthod is %d \n\r", number, sqrt); pc.printf("Total time of execution for sqrt of(%d)is %f \n\r", number, readValue); pc.printf("Number of CPU cycles for sqrt(%d): %d\n\r\n\r", number, (int)cpuCycles); } /*---------------------------------------------------------------------------- MAIN function *----------------------------------------------------------------------------*/ /** * @brief Main function * * Detailed description of the main */ int main(void){ volatile int r, j=0; double timer_read = 0.0; double sum = 0; pc.printf("/*----------------------------------------------------------------------------*/\r\n\r\n"); pc.printf("Frequency of KL25Z (ARM Cortex M0+): 48 MHZ\n\r\n\r"); timer.start(); timer.reset(); r = my_sqrt(2); // should be 1 timer_read = timer.read(); printCpuCycles(timer_read, 2, r); sum = sum + timer_read; timer.reset(); r = my_sqrt(4); // should be 2 timer_read = timer.read(); printCpuCycles(timer_read, 4, r); sum = sum + timer_read; timer.reset(); r = my_sqrt(22); // should be 4 timer_read = timer.read(); printCpuCycles(timer_read, 22, r); sum = sum + timer_read; timer.reset(); r = my_sqrt(121); // should be 11 timer_read = timer.read(); printCpuCycles(timer_read, 121, r); sum = sum + timer_read; pc.printf("Total time of operation: %f\n\r\n\r", sum); sum = sum * 48000000; pc.printf("CPU cycles: %d\n\r\n\r", (int)(sum)); pc.printf("/*----------------------------------------------------------------------------*/\r\n\r\n"); } // *******************************ARM University Program Copyright © ARM Ltd 2014*************************************/