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92 www.xilinx.com PicoBlaze 8-bit Embedded Microcontroller
UG129 (v1.1.2) June 24, 2008
Appendix : PicoBlaze Instruction Set and Event Reference
R
Pseudocode
sX Å (sX + Operand) mod 256; always an 8-bit result
if ( (sX + Operand) > 255 ) then
CARRY Å 1
else
CARRY Å 0
endif
if ( ((sX + Operand) = 0) or ((sX + Operand) = 256) ) then
ZERO Å 1
else
ZERO Å 0
endif
PC Å PC + 1
Registers/Flags Altered
Registers: sX, PC
Flags: CARRY, ZERO
ADDCY sX, Operand —Add Operand to Register sX with Carry
The ADDCY instruction performs an addition of two 8-bit operands and adds an additional
‘1’ if the CARRY flag was set by a previous instruction, as shown in Figure C-2. The first
operand is any register, which also receives the result of the operation. A second operand
is also any register or an 8-bit constant value. Flags are affected by this operation.
Example
Operand is a register location, sY, or an immediate byte-wide constant, kk.
ADDCY sX, sY; Add register. sX = sX + sY + CARRY
ADDCY sX, kk; Add immediate. sX = sX + kk + CARRY
Description
Operand and CARRY flag are added to register sX. The ZERO and CARRY flags are set
appropriately.
Figure C-2: ADDCY Instruction
Register sX
Register sY or
Literal kk
CARRY
Carry Out Carry In
UG129_aC_02_051604