SAA7391H Philips Semiconductors, SAA7391H Datasheet - Page 51

• Manufacturer Part Number: SAA7391H
• Description: ATAPI CD-R block encoder/decoder
• Manufacturer: Philips Semiconductors

Philips Semiconductors
Table 86 Decoding ‘chan’ bits
7.5.7
Table 87 Decoding bits 7 and 6 of HOSTSUBBLKOFFSETX-H (note 1)
Note
1. The last Form bit is the LSB of the byte that is situated at offset 12 in the current segment pointed at by
7.5.8
If either bit 6 or bit 7 are set in the HOSTRELOADFLAGS
register, then when the HOSTRELOADCOUNT register
becomes zero, the value of HOSTCURSEGCNT will be
copied from HOSTNEXTSEGCOUNT and
HOSTRELSEGMENT will be copied from
HOSTNEXTSEG.
This causes the host transfer process to continue looping
over the same region of memory in emulation of the
Chaucer and Sequioia devices.
At the same time one of the bits HOSTRELOADFLAGS
(bits 7 and 6) is reset on reload of the registers. The other
bit retains its value. Therefore:
1997 Aug 01
Single auto-reload is allowed: HOSTRELOADFLAGS
(bits 7 and 6) = 1 0
No auto-reload: HOSTRELOADFLAGS
(bits 7 and 6) = 0 0; pointer can be used as sub-block
extent 3
Multiple auto-reload: HOSTRELOADFLAGS
(bits 7 and 6) = 0 1.
ATAPI CD-R block encoder/decoder
VALUE
HOSTCURSEG. This is the stored Form byte in the header.
BIT
00
01
10
11
7
6
H
A
PROGRAMMING
UTOMATIC BLOCK POINTER RELOAD
OST INTERFACE
autoform
NAME
form
DMA
VALUE
0
1
0
1
SPECIAL BITS
unconditional transfer
only transfer if previous Form bit matches bit 6
match last Form bit = 0, perform this transfer if success else reload host registers
match last Form bit = 1, perform this transfer if success else reload host registers
use extent 0 to 3 (see also Section 7.5.8)
use extent 0 to 1
use extent 0 to 2
51
DESCRIPTION
use extent 0
7.5.9
The host interface is optimized for the normal read
commands, handling all data transfers or contiguous data
plus header requests automatically, with auto Form
detection in Mode 2.
If discontinuous data which requires more than
3 sub-block extents e.g. for READ-CD is required then it is
necessary to program the HOSTCURSEG,
HOSTBYTECOUNT and HOSTBYTEOFFSET for each
discontinuous part of each block that is to be transferred.
Writing the value 1 into the ‘hostblock’ will cause the
transfer to take place.
DESCRIPTION
DMA
INTERFACE
TRANSFER PROGRAMMING OF THE HOST
Objective specification
SAA7391