eam_external_read_data.asm

义隆公司eSLZ000 dsp处理芯片一个播放midi的样例程序。

.IFNDEF	@_LIB_EXTERNAL_READ_DATA_ASM
@_LIB_EXTERNAL_READ_DATA_ASM		.EQU		1


.CODE

;*****************************************************************************************
; SUBROUTINE: EXTERNAL_READ_WORD
; DESCRIPTION: Read one word data from external memory(Mode: Byte Mode).
;              SPI FLASH is the default external memory type.
;              
;              If user want to use SPI for the external memory access method, such as Melody/Speech spi application, you should remove the "//" from
;                  //.EXTERN @_LIB_F_SPI_RX_2BYTE
;                  //CALL @_LIB_F_SPI_RX_2BYTE
;              If user wants to use other type of external memory,
;              the subroutine of manipulating external memory remains to be designed by user for their specific applications, 
;              and user needs to replace the following code with designed code
;                  //.EXTERN @_LIB_F_SPI_RX_2BYTE
;                  //CALL @_LIB_F_SPI_RX_2BYTE 
; 
; The external memory read subroutine must follow four rules:
; 1. The input address will be stored in R1(high address) and R0(low address) by speech decoder, 
;    so external memory subroutine must get address from R1 and R0.
; 2. The external memory must be set as byte mode.
; 3. In external memory subroutine, two consecutive bytes must be combined as one word.
; 4. The output data(word) of external memory subroutine must be put in R0.
;
;*****************************************************************************************

//.EXTERN @_LIB_F_SPI_RX_2BYTE

.GLOBAL S_EXTERNAL_READ_WORD
S_EXTERNAL_READ_WORD:
;********************************
;user can program code from here
;********************************
    //CALL @_LIB_F_SPI_RX_2BYTE 
RET

.GLOBAL M_EXTERNAL_READ_WORD
M_EXTERNAL_READ_WORD:
;********************************
;user can program code from here
;********************************    
    //CALL @_LIB_F_SPI_RX_2BYTE 
RET


.ENDIF		;@_LIB_EXTERNAL_READ_DATA_ASM