TCP/IP offload device with fast-path TCP ACK generating and transmitting ...

/* BEGINNING OF CODE THAT DOES ACK TX PROCESSING 7

AX_DAP: /"*** AX_DAP ""7

/*

*DO ACK PROCESSING.

*

* THE RCV DELACK TIMER HAS EXPIRED.

* FORMAT AND SEND AN ACK.
7

/*TI_LENL6 EQU L6 7

/* LNBPL8 EQU L8 LARGE INIC BUFFER PTR 7

/*TCP_CSUML11 EQU L11 7
/*SYS_SCR EQU SYS_SCR 7

/* GET A DRAM BUFFER TO PUT PCI PAYLOAD IN
JSR GETLDBUF;
TEST LNBPL8, JCF ZERO DAP0_1;
/* NO BUFFER - SEND EVENT AND TRY LATER 7
MOVE GRO EX_SACKC,
JSR SETOPEVNT;
JMP XFSM EXIT;

7

/* (LNBPL8). 7

r GO ON IF GOT A BUFFER 7

/* (THWD0L12)

DAP0_1:

/* SETUP CANNED HEADER. 7
CLR TI_LENL6,

JSR SETCANNEDHDDR; /* (TI_LENL6, TOTLENL10, TCP_CSUML11) 7

/* DMA TEMPLATE HDDR FROM SRAM TO DRAM BUFFER 7
/*SET CHKSUM INTO HEADER 7

ADDL ADDR_REGB TCBSRAML5 STCB_TEMPLATE+TPL_TCPCSUM|ADDR15;

/* READ TEMPLATE HEADER FROM SRAM 7
ANDL SYS_SCR TCP_CSUML11 H'FFFF';

SHFTR TCP_CSUML11 C16, LIT_TO_ADDR_REGA STCB_TCPCB+TCB_SHFLAGS;
ADD TCP_CSUML11 SYS_SCR, JCF ALU_B16 '$ + 2';

INCR TCP_CSUML11; /* ADD IN CARRY 7

BTEST SRAM1 TSF_VLANC, JCT ZERO '$ + 2'; /* GO NO VLAN TAG 7

FIG. 4A

ADD ADDR_REGB VLAN_TAG_SZEC;

XOR TCP_CSUML11 MINUSJI, WSRAM2_XPOSE;

/*

* SET FRAME LEN INTO TEMPLATE HEADER FOR MAC SEQR.

* FRAMELEN = TEMPLATE HDR LEN - 2

*/

MOVEL ADDR_REGA STCB_TEMPLATE+TPL_TMPLTLEN; /* POINT TO TEMPLATE LENGTH */

MOVE CRO SRAM2, LIT_TO_ADDR_REGB STCB_XMTBYTCNT;

COMP CRO MIN_FRAME_LEN, JCT LT '$ + 3';

/* MAKE SURE FRAME IS MIN LENGTH */

SUBL NULL CRO XMT_HDDR_SIZE_SRAM, WSRAM4; /* TEMPLATE HDR - 2 7
JMP '$ + 2';

MOVEL SRAM4 ETHER_MIN_TU; /* MIN ETHER FRAME LEN = 60 (+CRC) */
ADD CRO SIZEOF_XMITHDR+7C; I* PREPARE TO ROUNDUP XFER SIZE 7
MOVE RAM_BASE PDDSCPTR, LIT_TO_ADDR_REGB DMA_CMD_WD;
ANDNL SRAM4+ CRO H'3';

/* PDES->IXFR_SZ ROUNDED TO 8-BYTE BNDRY 7

MOVE SRAM4+ LNBPL8; /* PDES->DST_ADDR = 7

ADDL SRAM4 TCBSRAML5 STCB_XMIT_BUFFER; /* PDES->SRC_ADDR = 7

/* XXXDMA ORL CH_CMD CTXT_RPROC CCR_S2D; 7

/* SET UP TO DMA THE ACK FROM SRAM TO DRAM 7

MOVE Q_CTRL Q_S2DC; /* SELECT S2D DMA 7

MOVE Q_DATA PDDSCPTR;

JCF Q_OP_DONE'$-1';

MOVE CTXT_RTNADL14 PC, JMP PROC_SUSPEND; /* SUSPEND 7
MOVE RAM_BASE TCBSRAML5; /* RESUME 7

FIG. 4B