Compaq 21264 - Manual (Page 182)

5–40 Internal Processor Registers Alpha 21264/EV67 Hardware Reference Manual
Cbox CSRs and IPRs
; SET_DIRTY_ENABLE = 6
; BC_BANK_ENABLE = 1
; BC_WRT_STS = 0
;
; The value for the write_many chain is based on Table 5–25.
;
; The value is sampled from MSB, 6 bits at a time, as it is written
; to EV6__DATA. Therefore, before the value can be shifted in, it must be
; inverted on a by 6 basis. The code then writes out 6 bits at a time,
; shifting right by 6 after each write.
;
; So the following transformation is done on the write_many value:
;
; [35:30]|[29:24]|[23:18]|[17:12]|[11:06]|[05:00]
=>
; [05:00]|[11:06]|[17:12]|[23:18]|[29:24]|[35:30]
;
;
WRITE_MANY chain = 0x07FBFFFFD
; value to be shifted in = 0xF7FFEFFC1
;
; Before the chain can be written, I_CTL[SBE] must be disabled,
; and the code must be forced into the Icache.
;
ALIGN_CACHE_BLOCK <^x47FF041F>; align with nops
mb ; wait for MEM-OP’s to complete
lda r0, ^x0086(r31) ; load I_CTL.....
hw_mtpr r0, EV6__I_CTL ; .....SDE=2, IC_EN=3, SBE=0
br r0, . ; create dest address
addq r0, #17, r0 ; finish computing dest address
hw_mtpr r31, EV6__IC_FLUSH ; flush the Icache
bne r31, . ; separate retires
hw_jmp_stall (r0) ; force flush
ALIGN_CACHE_BLOCK <^x47FF041F> ; align with nops
bc_config:
mb ; pull this block in Icache
lda r1, ^xFFC1(r31) ; data[15:00] = 0xFFC1
ldah r0, ^x7FFE(r31) ; data[31:16] = 0x7FFE
zap r1, #^x0c, r1 ; clear out bits [31:16]
bis r1, r0, r1 ; or in bits [31:16]
addq r31, #6, r0 ; shift in 6 x 6 bits
bc_config_shift_in:
hw_mtpr r1, EV6__DATA ; shift in 6 bits
subq r0, #1, r0 ; decrement R0
beq r0, bc_config_done ; done if R0 is zero
srl r1, #6, r1 ; align next 6 bits
br r31, bc_config_shift_in ; continue shifting
bc_config_done:
hw_mtpr r31, <EV6__MM_STAT ! 64> ; wait until last shift
beq r31, bc_config_end ; predicts fall thru
br r31, .-4 ; predict infinite loop
bis r31, r31, r31 ; nop
bis r31, r31, r31 ; nop
bc_config_end: