
ADDRESS SPACES
S3C8248/C8245/P8245/C8247/C8249/P8249
2-10
16-Byte
Contiguous
working
Register block
Register File
Contains 32
8-Byte Slices
0 0 0 0 0 X X X
RP1
1 1 1 1 0 X X X
RP0
0H (R0)
7H (R15)
F0H (R0)
F7H (R7)
8-Byte Slice
8-Byte Slice
Figure 2-7. Non-Contiguous 16-Byte Working Register Block
+
+
PROGRAMMING TIP — Using the RPs to Calculate the Sum of a Series of Registers
Calculate the sum of registers 80H–85H using the register pointer. The register addresses from 80H through 85H
contain the values 10H, 11H, 12H, 13H, 14H, and 15 H, respectively:
SRP0
#80H
; RP0
←
80H
ADD
R0,R1
; R0
←
R0 + R1
ADC
R0,R2
; R0
←
R0 + R2 + C
ADC
R0,R3
; R0
←
R0 + R3 + C
ADC
R0,R4
; R0
←
R0 + R4 + C
ADC
R0,R5
; R0
←
R0 + R5 + C
The sum of these six registers, 6FH, is located in the register R0 (80H). The instruction string used in this
example takes 12 bytes of instruction code and its execution time is 36 cycles. If the register pointer is not used
to calculate the sum of these registers, the following instruction sequence would have to be used:
ADD
80H,81H
; 80H
←
(80H) + (81H)
ADC
80H,82H
; 80H
←
(80H) + (82H) + C
ADC
80H,83H
; 80H
←
(80H) + (83H) + C
ADC
80H,84H
; 80H
←
(80H) + (84H) + C
ADC
80H,85H
; 80H
←
(80H) + (85H) + C
Now, the sum of the six registers is also located in register 80H. However, this instruction string takes 15 bytes of
instruction code rather than 12 bytes, and its execution time is 50 cycles rather than 36 cycles.
Summary of Contents for C8245
Page 31: ...ADDRESS SPACES S3C8248 C8245 P8245 C8247 C8249 P8249 2 20 NOTES ...
Page 107: ...INTERRUPT STRUCTURE S3C8248 C8245 P8245 C8247 C8249 P8249 5 18 NOTES ...
Page 195: ...INSTRUCTION SET S3C8248 C8245 P8245 C8247 C8249 P8249 6 88 NOTES ...
Page 221: ...I O PORTS S3C8248 C8245 P8245 C8247 C8249 P8249 9 16 NOTES ...
Page 245: ...16 BIT TIMER 0 1 S3C8248 C8245 P8245 C8247 C8249 P8249 12 10 NOTES ...
Page 249: ...WATCH TIMER S3C8248 C8245 P8245 C8247 C8249 P8249 13 4 NOTES ...
Page 267: ...A D CONVERTER S3C8248 C8245 P8245 C8247 C8249 P8249 15 6 NOTES ...
Page 299: ...S3P8245 P8249 OTP S3C8248 C8245 P8245 C8247 C8249 P8249 21 8 NOTES ...
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