SDKZSPF LSI, SDKZSPF Datasheet - Page 63

• Manufacturer Part Number: SDKZSPF
• Manufacturer: LSI

Specifications of SDKZSPF

• Lead Free Status / Rohs Status: Supplier Unconfirmed

Table 3.5
1. ANSI C code does not use intrinsics, circular buffers, or the q15 data type.
2. This column describes the requirements on an assembly function called from C code.
3. With sdcc/zdxcc, the sat bit of %fmode can affect ANSI C code because of the add and subtract
4. With sdcc/zdxcc, the q15 mode bit affects ANSI C code if the -minfer_mac option is used.
5. The sre bit of %fmode affects ANSI C code because of the shra and shra.e instructions. Only per-
6. With sdcc/zdxcc, the mre mode bit affects ANSI C code if the -minfer_mac option is used.
7. This bit is ZSP400 specific and selects/deselects the use of shadow registers. Compiled code oper-
8. For ZSPG2, these bits affect the behavior of r14 and r15. They exist for compatibility with ZSP400.
9. This bit controls whether instructions are fetched from internal or external memory. Compiled code
10. This bit controls whether data is fetched from internal or external memory. Compiled code operates
%smode
Register
Mode
instructions. ANSI C code expects unsaturated arithmetic. If saturated arithmetic is required for some
intrinsics, it is safest to enable saturation over as small a region of code as possible, because the
sat bit also affects adds and subtracts that must not be saturated (e.g. address arithmetic, stack
pointer manipulation, counters, etc.). If the -minfer_mac option is used, the compiler also generates
mac and macn instructions, which are also affected by the sat bit.
form right shifts of signed variables when the sre bit is cleared.
ates correctly with either shadow registers or nonshadow registers.
They should never be set in code compiled with zdcc. When using sdcc/zdxcc, to prevent these bits
from affecting ANSI C code, clear these bits when the portion of code requiring circular buffers is
exited.
operates correctly when it resides in internal or external memory, though normally it resides in inter-
nal memory.
correctly when data resides in internal or external memory, though normally data resides in internal
memory. Note that data includes the stack, and that compiled code does not operate correctly if glo-
bal data resides in one memory and the stack resides in another memory.
Register
Effect of Mode Bits on Compiler-Generated Code (Cont.)
Mode
ddr
cbX
shd
dir
Bit
sis
lis
10
9
7
8
Compiler Conventions
Copyright © 1999-2003 by LSI Logic Corporation. All rights reserved.
Affects ANSI C
zdxcc
sdcc
yes
Code
yes
yes
yes
yes
yes
1
zdcc
n/a
Required Entry
zdxcc
sdcc
x
0
0
Value
0
x
x
zdcc
n/a
x
x
On Return From
Required Value
zdxcc
serve
sdcc
pre-
0
0
preserve
preserve
Call
0
2
serve
serve
zdcc
pre-
pre-
n/a
May be Modified
Within Function
zdxcc
sdcc
yes
no
no
no
no
no
zdcc
n/a
no
3-9