📄 net_util_a.s
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@********************************************************************************************************
@ uC/TCP-IP
@ The Embedded TCP/IP Suite
@
@ (c) Copyright 2003-2007; Micrium, Inc.; Weston, FL
@
@ All rights reserved. Protected by international copyright laws.
@
@ uC/TCP-IP is provided in source form for FREE evaluation, for educational
@ use or peaceful research. If you plan on using uC/TCP-IP 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/TCP-IP. 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.
@********************************************************************************************************
@********************************************************************************************************
@
@ NETWORK UTILITY LIBRARY
@
@ ARM
@ GNU Compiler
@
@ Filename : net_util_a.s
@ Version : V1.91
@ Programmer(s) : JDH
@********************************************************************************************************
@ Note(s) : (1) Assumes ARM CPU mode configured for Little Endian.
@********************************************************************************************************
@********************************************************************************************************
@ PUBLIC FUNCTIONS
@********************************************************************************************************
.global NetUtil_16BitSumDataCalcAlign_32
@********************************************************************************************************
@ CODE GENERATION DIRECTIVES
@********************************************************************************************************
.code 32
@$PAGE
@********************************************************************************************************
@ NetUtil_16BitSumDataCalcAlign_32()
@
@ Description : Calculate 16-bit sum on 32-bit word-aligned data.
@
@ Argument(s) : pdata_32 Pointer to 32-bit word-aligned data (see Note #2).
@
@ size Size of data.
@
@ Return(s) : 16-bit sum (see Notes #1 & #3).
@
@ Caller(s) : NetUtil_16BitSumDataCalc().
@
@ This function is an INTERNAL network protocol suite function & SHOULD NOT be called by
@ application function(s).
@
@ Note(s) : (1) Computes the sum of consecutive 16-bit values.
@
@ (2) Since many word-aligned processors REQUIRE that multi-octet words be located on word-
@ aligned addresses, sum calculation REQUIREs that 32-bit words are accessed on addresses
@ that are multiples of 4 octets.
@
@ (3) The 16-bit sum MUST be returned in Big Endian/Network order.
@
@ See 'net_util.c NetUtil_16BitSumDataCalc() Note #5b'.
@
@ (a) Assumes Little Endian CPU Mode (see 'net_util_a.s Note #1') thus requiring the
@ 16-bit octets of the 32-bit data to be swapped.
@
@ #### However, the 16-bit octets COULD be swapped after the 16-bit sum is fully
@ calculated.
@********************************************************************************************************
@ CPU_INT32U NetUtil_16BitSumDataCalcAlign_32 (void *pdata_32, @ ==> R0
@ CPU_INT32U size) @ ==> R1
@ @ sum ==> R2
NetUtil_16BitSumDataCalcAlign_32:
STMFD SP!, {R2-R12}
MOV R2, #0
B NetUtil_16BitSumDataCalcAlign_32_0
NetUtil_16BitSumDataCalcAlign_32_1:
LDMIA R0!, {R5-R12} @ Calc sum of sixteen 16-bit words ...
@ ... using eight 32-bit CPU regs.
MOV R3, R5, LSR #16
MOV R4, R3, LSR #8
AND R3, R3, #0xFF
ORR R4, R4, R3, LSL #8
ADD R2, R4, R2
MOV R3, R5, LSL #16
MOV R3, R3, LSR #16
MOV R4, R3, LSR #8
AND R3, R3, #0xFF
ORR R4, R4, R3, LSL #8
ADD R2, R4, R2
MOV R3, R6, LSR #16
MOV R4, R3, LSR #8
AND R3, R3, #0xFF
ORR R4, R4, R3, LSL #8
ADD R2, R4, R2
MOV R3, R6, LSL #16
MOV R3, R3, LSR #16
MOV R4, R3, LSR #8
AND R3, R3, #0xFF
ORR R4, R4, R3, LSL #8
ADD R2, R4, R2
MOV R3, R7, LSR #16
MOV R4, R3, LSR #8
AND R3, R3, #0xFF
ORR R4, R4, R3, LSL #8
ADD R2, R4, R2
MOV R3, R7, LSL #16
MOV R3, R3, LSR #16
MOV R4, R3, LSR #8
AND R3, R3, #0xFF
ORR R4, R4, R3, LSL #8
ADD R2, R4, R2
@$PAGE
MOV R3, R8, LSR #16
MOV R4, R3, LSR #8
AND R3, R3, #0xFF
ORR R4, R4, R3, LSL #8
ADD R2, R4, R2
MOV R3, R8, LSL #16
MOV R3, R3, LSR #16
MOV R4, R3, LSR #8
AND R3, R3, #0xFF
ORR R4, R4, R3, LSL #8
ADD R2, R4, R2
MOV R3, R9, LSR #16
MOV R4, R3, LSR #8
AND R3, R3, #0xFF
ORR R4, R4, R3, LSL #8
ADD R2, R4, R2
MOV R3, R9, LSL #16
MOV R3, R3, LSR #16
MOV R4, R3, LSR #8
AND R3, R3, #0xFF
ORR R4, R4, R3, LSL #8
ADD R2, R4, R2
MOV R3, R10, LSR #16
MOV R4, R3, LSR #8
AND R3, R3, #0xFF
ORR R4, R4, R3, LSL #8
ADD R2, R4, R2
MOV R3, R10, LSL #16
MOV R3, R3, LSR #16
MOV R4, R3, LSR #8
AND R3, R3, #0xFF
ORR R4, R4, R3, LSL #8
ADD R2, R4, R2
MOV R3, R11, LSR #16
MOV R4, R3, LSR #8
AND R3, R3, #0xFF
ORR R4, R4, R3, LSL #8
ADD R2, R4, R2
MOV R3, R11, LSL #16
MOV R3, R3, LSR #16
MOV R4, R3, LSR #8
AND R3, R3, #0xFF
ORR R4, R4, R3, LSL #8
ADD R2, R4, R2
MOV R3, R12, LSR #16
MOV R4, R3, LSR #8
AND R3, R3, #0xFF
ORR R4, R4, R3, LSL #8
ADD R2, R4, R2
MOV R3, R12, LSL #16
MOV R3, R3, LSR #16
MOV R4, R3, LSR #8
AND R3, R3, #0xFF
ORR R4, R4, R3, LSL #8
ADD R2, R4, R2
SUB R1, R1, #(4*8*1)
NetUtil_16BitSumDataCalcAlign_32_0:
CMP R1, #(4*8*1) @ end of loop
BCS NetUtil_16BitSumDataCalcAlign_32_1
B NetUtil_16BitSumDataCalcAlign_32_2
@$PAGE
NetUtil_16BitSumDataCalcAlign_32_3:
LDMIA R0!, {R5} @ Calc sum of two 16-bit words ...
@ ... using one 32-bit CPU reg.
MOV R3, R5, LSR #16
MOV R4, R3, LSR #8
AND R3, R3, #0xFF
ORR R4, R4, R3, LSL #8
ADD R2, R4, R2
MOV R3, R5, LSL #16
MOV R3, R3, LSR #16
MOV R4, R3, LSR #8
AND R3, R3, #0xFF
ORR R4, R4, R3, LSL #8
ADD R2, R4, R2
SUB R1, R1, #(4*1*1)
NetUtil_16BitSumDataCalcAlign_32_2:
CMP R1, #(4*1*1) @ end of loop
BCS NetUtil_16BitSumDataCalcAlign_32_3
MOV R0, R2
LDMFD SP!, {R2-R12}
BX LR @ return
.ltorg
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