Changeset 94
- Timestamp:
- Sep 21, 2010, 11:49:04 AM (10 years ago)
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- 1 edited
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C-semantics/8051-Memory/memory.tex
r82 r94 77 77 \put(164,324){\makebox(80,0){paged access}} 78 78 \put(164,310){\makebox(80,0){direct/indirect}} 79 \put(163,235){\makebox(0,0)[r]{ 100h}}79 \put(163,235){\makebox(0,0)[r]{80h}} 80 80 \put(164,228){\makebox(80,0){\vdots}} 81 81 \put(164,210){\makebox(80,0){direct/indirect}} … … 124 124 `variables' which access the \emph{Special Function Registers} (SFR). 125 125 Pointers to these types are not allowed. [Does this match the 8051 instruction 126 set? ]126 set? CSC: in what sense? you cannot indirectly address any SFR register nor an SFR bit in 8051, so maybe this is the reason; it makes sense anyway.] 127 127 128 128 These are all defined in Section~3.4.1 of the \sdcc\ manual. … … 152 152 explicit addresses except for \lstinline'volatile' variables. 153 153 \item Leave out bit variables(?), provide `external functions' in the CompCert 154 sense for bit access to SFRs but compile them to the corresponding instruction. 154 sense for bit access to SFRs but compile them to the corresponding instruction.\\ 155 CSC: this is unclear to me. In order to address SFR's bits, this is easily achieved. But for the first half of the bit address space (the real bits), this is not the case since only a few bytes can be accessed this way. Thus, if the compiler wants to exploit bit variables, it must do some spilling and keep the bits in the right memory area. 155 156 \item Allow casting (and automatic promotion?) to generic pointer types. 156 157 \item Only provide equality, ordering and subtraction operations on pointer
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