lib_mem_a.asm
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- ;********************************************************************************************************
; uC/LIB
; CUSTOM LIBRARY MODULES
;
; (c) Copyright 2004-2008; Micrium, Inc.; Weston, FL
;
; All rights reserved. Protected by international copyright laws.
;
; uC/LIB is provided in source form for FREE evaluation, for educational
; use or peaceful research. If you plan on using uC/LIB in a commercial
; product you need to contact Micrium to properly license its use in your
; product. We provide ALL the source code for your convenience and to
; help you experience uC/LIB. The fact that the source code is provided
; does NOT mean that you can use it without paying a licensing fee.
;
; Knowledge of the source code may NOT be used to develop a similar product.
;
; Please help us continue to provide the Embedded community with the finest
; software available. Your honesty is greatly appreciated.
;********************************************************************************************************
;********************************************************************************************************
;
; STANDARD MEMORY OPERATIONS
;
; ARM-Cortex-M3
; RealView Development Suite
; RealView Microcontroller Development Kit (MDK)
; ARM Developer Suite (ADS)
; Keil uVision
;
; Filename : lib_mem_a.asm
; Version : V1.25
; Programmer(s) : JDH
; BAN
;********************************************************************************************************
; Note(s) : (1) NO compiler-supplied standard library functions are used in library or product software.
;
; (a) ALL standard library functions are implemented in the custom library modules :
;
; (1) <Custom Library Directory>lib*.*
;
; (2) <Custom Library Directory>Ports<cpu><compiler>lib*_a.*
;
; where
; <Custom Library Directory> directory path for custom library software
; <cpu> directory name for specific processor (CPU)
; <compiler> directory name for specific compiler
;
; (b) Product-specific library functions are implemented in individual products.
;
; (2) Assumes ARM CPU mode configured for Little Endian.
;********************************************************************************************************
;********************************************************************************************************
; PUBLIC FUNCTIONS
;********************************************************************************************************
EXPORT Mem_Copy
;********************************************************************************************************
; CODE GENERATION DIRECTIVES
;********************************************************************************************************
AREA |.text|, CODE, READONLY, ALIGN=2
THUMB
REQUIRE8
PRESERVE8
;$PAGE
;********************************************************************************************************
; Mem_Copy()
;
; Description : Copy data octets from one buffer to another buffer.
;
; Argument(s) : pdest Pointer to destination memory buffer.
;
; psrc Pointer to source memory buffer.
;
; size Number of data buffer octets to copy.
;
; Return(s) : none.
;
; Caller(s) : Application.
;
; Note(s) : (1) Null copies allowed (i.e. 0-octet size).
;
; (2) Memory buffers NOT checked for overlapping.
;
; (3) Modulo arithmetic is used to determine whether a memory buffer starts on a 'CPU_ALIGN'
; address boundary.
;
; (4) ARM Cortex-M3 processors use a subset of the ARM Thumb-2 instruction set which does
; NOT support 16-bit conditional branch instructions but ONLY supports 8-bit conditional
; branch instructions.
;
; Therefore, branches exceeding 8-bit, signed, relative offsets :
;
; (a) CANNOT be implemented with conditional branches; but ...
; (b) MUST be implemented with non-conditional branches.
;********************************************************************************************************
; void Mem_Copy (void *pdest, ; ==> R0
; void *psrc, ; ==> R1
; CPU_SIZE_T size) ; ==> R2
Mem_Copy
- CMP R0, #0
- BNE Mem_Copy_1
- BX LR ; return if pdest == NULL
- Mem_Copy_1
- CMP R1, #0
- BNE Mem_Copy_2
- BX LR ; return if psrc == NULL
- Mem_Copy_2
- CMP R2, #0
- BNE Mem_Copy_3
- BX LR ; return if size == 0
- Mem_Copy_3
- STMFD SP!, {R3-R12} ; save registers on stack
- ;$PAGE
Chk_Align_32 ; check if both dest & src 32-bit aligned
- AND R3, R0, #0x03
- AND R4, R1, #0x03
- CMP R3, R4
- BNE Chk_Align_16 ; not 32-bit aligned, check for 16-bit alignment
- RSB R3, R3, #0x04 ; compute 1-2-3 pre-copy bytes (to align to the next 32-bit boundary)
- AND R3, R3, #0x03
- Pre_Copy_1
- CMP R3, #1 ; copy 1-2-3 bytes (to align to the next 32-bit boundary)
- BCC Copy_32_1 ; start real 32-bit copy
- CMP R2, #1 ; check if any more data to copy
BCS Pre_Copy_1_Cont
B Mem_Copy_END ; no more data to copy (see Note #4b)
- Pre_Copy_1_Cont
- LDRB R4, [R1], #1
- STRB R4, [R0], #1
- SUB R3, R3, #1
- SUB R2, R2, #1
- B Pre_Copy_1
-
Chk_Align_16 ; check if both dest & src 16-bit aligned
- AND R3, R0, #0x01
- AND R4, R1, #0x01
- CMP R3, R4
- BEQ Pre_Copy_2
- B Copy_08_1 ; not 16-bit aligned, start 8-bit copy (see Note #4b)
- Pre_Copy_2
- CMP R3, #1 ; copy 1 byte (to align to the next 16-bit boundary)
- BCC Copy_16_1 ; start real 16-bit copy
- LDRB R4, [R1], #1
- STRB R4, [R0], #1
- SUB R3, R3, #1
- SUB R2, R2, #1
- B Pre_Copy_2
-
Copy_32_1
- CMP R2, #(04*10*09) ; Copy 9 chunks of 10 32-bit words (360 octets per loop)
- BCC Copy_32_2
- LDMIA R1!, {R3-R12}
- STMIA R0!, {R3-R12}
- LDMIA R1!, {R3-R12}
- STMIA R0!, {R3-R12}
- LDMIA R1!, {R3-R12}
- STMIA R0!, {R3-R12}
- LDMIA R1!, {R3-R12}
- STMIA R0!, {R3-R12}
- LDMIA R1!, {R3-R12}
- STMIA R0!, {R3-R12}
- LDMIA R1!, {R3-R12}
- STMIA R0!, {R3-R12}
- LDMIA R1!, {R3-R12}
- STMIA R0!, {R3-R12}
- LDMIA R1!, {R3-R12}
- STMIA R0!, {R3-R12}
- LDMIA R1!, {R3-R12}
- STMIA R0!, {R3-R12}
- SUB R2, R2, #(04*10*09)
- B Copy_32_1
- Copy_32_2
- CMP R2, #(04*10*01) ; Copy chunks of 10 32-bit words (40 octets per loop)
- BCC Copy_32_3
- LDMIA R1!, {R3-R12}
- STMIA R0!, {R3-R12}
- SUB R2, R2, #(04*10*01)
- B Copy_32_2
- Copy_32_3
- CMP R2, #(04*01*01) ; Copy remaining 32-bit words
- BCC Copy_16_1
- LDR R3, [R1], #4
- STR R3, [R0], #4
- SUB R2, R2, #(04*01*01)
- B Copy_32_3
-
;$PAGE
Copy_16_1
- CMP R2, #(02*01*16) ; Copy chunks of 16 16-bit words (32 bytes per loop)
- BCC Copy_16_2
- LDRH R3, [R1], #2
- STRH R3, [R0], #2
- LDRH R3, [R1], #2
- STRH R3, [R0], #2
- LDRH R3, [R1], #2
- STRH R3, [R0], #2
- LDRH R3, [R1], #2
- STRH R3, [R0], #2
- LDRH R3, [R1], #2
- STRH R3, [R0], #2
- LDRH R3, [R1], #2
- STRH R3, [R0], #2
- LDRH R3, [R1], #2
- STRH R3, [R0], #2
- LDRH R3, [R1], #2
- STRH R3, [R0], #2
- LDRH R3, [R1], #2
- STRH R3, [R0], #2
- LDRH R3, [R1], #2
- STRH R3, [R0], #2
- LDRH R3, [R1], #2
- STRH R3, [R0], #2
- LDRH R3, [R1], #2
- STRH R3, [R0], #2
- LDRH R3, [R1], #2
- STRH R3, [R0], #2
- LDRH R3, [R1], #2
- STRH R3, [R0], #2
- LDRH R3, [R1], #2
- STRH R3, [R0], #2
- LDRH R3, [R1], #2
- STRH R3, [R0], #2
- SUB R2, R2, #(02*01*16)
- B Copy_16_1
- Copy_16_2
- CMP R2, #(02*01*01) ; Copy remaining 16-bit words
- BCC Copy_08_1
- LDRH R3, [R1], #2
- STRH R3, [R0], #2
- SUB R2, R2, #(02*01*01)
- B Copy_16_2
-
;$PAGE
Copy_08_1
- CMP R2, #(01*01*16) ; Copy chunks of 16 8-bit words (16 bytes per loop)
- BCC Copy_08_2
- LDRB R3, [R1], #1
- STRB R3, [R0], #1
- LDRB R3, [R1], #1
- STRB R3, [R0], #1
- LDRB R3, [R1], #1
- STRB R3, [R0], #1
- LDRB R3, [R1], #1
- STRB R3, [R0], #1
- LDRB R3, [R1], #1
- STRB R3, [R0], #1
- LDRB R3, [R1], #1
- STRB R3, [R0], #1
- LDRB R3, [R1], #1
- STRB R3, [R0], #1
- LDRB R3, [R1], #1
- STRB R3, [R0], #1
- LDRB R3, [R1], #1
- STRB R3, [R0], #1
- LDRB R3, [R1], #1
- STRB R3, [R0], #1
- LDRB R3, [R1], #1
- STRB R3, [R0], #1
- LDRB R3, [R1], #1
- STRB R3, [R0], #1
- LDRB R3, [R1], #1
- STRB R3, [R0], #1
- LDRB R3, [R1], #1
- STRB R3, [R0], #1
- LDRB R3, [R1], #1
- STRB R3, [R0], #1
- LDRB R3, [R1], #1
- STRB R3, [R0], #1
- SUB R2, R2, #(01*01*16)
- B Copy_08_1
- Copy_08_2
- CMP R2, #(01*01*01) ; Copy remaining 8-bit words
- BCC Mem_Copy_END
- LDRB R3, [R1], #1
- STRB R3, [R0], #1
- SUB R2, R2, #(01*01*01)
- B Copy_08_2
- Mem_Copy_END
- LDMFD SP!, {R3-R12} ; restore registers from stack
- BX LR ; return
- END
-
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