;;#############################################################################
;;
;; FILE:   f28004x_usdelay.asm
;;
;; TITLE:  Simple Delay Function
;;
;; DESCRIPTION:
;;
;;  This is a simple delay function that can be used to insert a specified
;;  delay into code.
;;  This function is only accurate if executed from internal zero-waitstate
;;  SARAM. If it is executed from waitstate memory then the delay will be
;;  longer then specified.
;;  To use this function:
;;   1 - update the CPU clock speed in the f28004x_examples.h
;;     file.
;;   2 - Call this function by using the DELAY_US(A) macro
;;     that is defined in the f28004x_device.h file.  This macro
;;     will convert the number of microseconds specified
;;     into a loop count for use with this function.
;;     This count will be based on the CPU frequency you specify.
;;   3 - For the most accurate delay
;;     - Execute this function in 0 waitstate RAM.
;;     - Disable interrupts before calling the function
;;       If you do not disable interrupts, then think of
;;       this as an "at least" delay function as the actual
;;       delay may be longer.
;;   The C assembly call from the DELAY_US(time) macro will
;;   look as follows:
;;   extern void Delay(long LoopCount);
;;         MOV   AL,#LowLoopCount
;;         MOV   AH,#HighLoopCount
;;         LCR   _Delay
;;   Or as follows (if count is less then 16-bits):
;;         MOV   ACC,#LoopCount
;;         LCR   _Delay
;;#############################################################################
;; $TI Release: F28004x Support Library v1.12.00.00 $
;; $Release Date: Fri Feb 12 18:57:27 IST 2021 $
;; $Copyright:
;// Copyright (C) 2021 Texas Instruments Incorporated - http://www.ti.com/
;//
;// Redistribution and use in source and binary forms, with or without 
;// modification, are permitted provided that the following conditions 
;// are met:
;// 
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;//   notice, this list of conditions and the following disclaimer.
;// 
;//   Redistributions in binary form must reproduce the above copyright
;//   notice, this list of conditions and the following disclaimer in the 
;//   documentation and/or other materials provided with the   
;//   distribution.
;// 
;//   Neither the name of Texas Instruments Incorporated nor the names of
;//   its contributors may be used to endorse or promote products derived
;//   from this software without specific prior written permission.
;// 
;// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
;// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
;// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
;// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 
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;// $
;;#############################################################################

       .def F28x_usDelay
       .sect ".TI.ramfunc"

        .global  __F28x_usDelay
F28x_usDelay:
        SUB    ACC,#1
        BF     F28x_usDelay,GEQ    ;; Loop if ACC >= 0
        LRETR

;There is a 9/10 cycle overhead and each loop
;takes five cycles. The LoopCount is given by
;the following formula:
;  DELAY_CPU_CYCLES = 9 + 5*LoopCount
; LoopCount = (DELAY_CPU_CYCLES - 9) / 5
; The macro DELAY_US(A) performs this calculation for you

;;#############################################################################
;; End of file
;;#############################################################################

