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[/] [zipcpu/] [trunk/] [rtl/] [core/] [idecode.v] - Rev 123

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Rev	Log message	Author	Age	Path
118	Fixes two bugs: 1) in the early branching code within the instruction decoder. This prevented the early branching from working when built with Xilinx's tools, while the code worked with Verilator. 2) The CPU was not working with the traditional cache and early branching disabled. These two bugs masked each other. The replacement code is simpler.	dgisselq	3139d 06h	/zipcpu/trunk/rtl/core/idecode.v
105	Fixed some nasty early branching bugs. Adjusted the Makefile to declare that cpudefs.h was automatically generated from cpudefs.v, and made sure that zipbones included the cpudefs.v so it could get the DEBUG_SCOPE define. In addition, the test.S was updated to test long jumps, the early branching bug we found, and all three early branching instructions: ADD #x,PC, LOC(PC),PC, and LDI #x,PC.	dgisselq	3163d 14h	/zipcpu/trunk/rtl/core/idecode.v
90	Removed MOV x(PC),PC from the list of possible early branching instructions. ADD X,PC and LDI X,PC are now the only recognized early branching instructions. This was done to spare logic, although I don't think I spared more than a LUT or two.	dgisselq	3204d 08h	/zipcpu/trunk/rtl/core/idecode.v
71	This contains a bunch of bug fixes. (A lot ...) For example, the pipeline stall code has also seriously changed, to fixed the pipeline memory load/op stage conflict, while maintaining no-stall operation for operands that don't need an offset. This had a cascading effect, however, so that the multiply could no longer complete in a single cycle. Therefore, the timing on the multiplies was slowed down to two cycles from a single cycle. (It's the only two-cycle ALU operation ...) The illegal instruction code has also been fixed, so that illegal instructions no longer stalls the prefetch bus.	dgisselq	3235d 09h	/zipcpu/trunk/rtl/core/idecode.v
69	This implements the "new Instruction Set" architecture for the Zip CPU. It's a massive change set, that touches just about everything but probably not enough of everything. Please see the spec.pdf for a description of this new architecture.	dgisselq	3241d 14h	/zipcpu/trunk/rtl/core/idecode.v

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