The Singaporean expressway networks are connected with Malaysian expressway networks via Ayer Rajah Expressway (connects with the Second Link Expressway in Malaysia) and Bukit Timah Expressway (connects with the Johor Bahru Eastern Dispersal Link Expressway via Johor–Singapore Causeway). As of 2014, there are 163 kilometres (101 mi) of expressways in Singapore. Studies about the feasibility of additional expressways are ongoing.Ĭonstruction on the first expressway, the Pan Island Expressway, started in 1966. They usually have three to four lanes in each direction, although there are two-lane carriageways at many expressway intersections and five-lane carriageways in some places. All of them are dual carriageways with grade-separated access. Construction of the system was authorized when construction of the Pan Island Expressway began in 1962. The Expressways of Singapore are special roads that allow motorists to travel quickly from one urban area to another.
It doesn’t bother with $t0-$t9.The Bukit Timah Expressway is part of the Asian Highway Network. They are referred to as $s0-$s7 if the callee uses $s0-$s7 it must save them when the procedure is entered and restore them on return (callee saved). 8 registers 16-23 are designated as saved registers that must be preserved by the callee. They are referred to as $t0-$t9 if the caller uses $t0-$t9 it must save them before the call and restore them on return (caller-saved). MIPS assembler conventions are: 10 registers (8-15 and 24-25) are designated as temporary registers that need not be preserved by the callee. The alternative is to define and adhere to a protocol where all procedures assume that certain registers need not be saved and restored across a procedure call. When too many registers are spilled, performance suffers. $sn and $tm In the example the procedure saved and restored every register it intended to use without knowing whether they were used by the caller. CS555A – Real-Time Embedded Systems Stevens Institute of Technology CS555A – Real-Time Embedded Systems Stevens Institute of Technology Fall 2014, arz 11 Now the callee can use reg1 as before Increasing Addresses Stack Grows Down Stack Pointer: $sp Stack “Top” CS555A – Real-Time Embedded Systems Stevens Institute of Technology CS555A – Real-Time Embedded Systems Stevens Institute of Technology Fall 2014, arz 10Įxample - Continued Save current values on stack.Before the procedure returns, it must restore reg16 to original value.
Popping a Register From the Stack +4 Carnegie Mellon Stack “Bottom” Pushing a Register on the Stack Suppose the called procedure wants to use reg16 It must push register reg16 to save it subi $sp, $sp, 4 Makes room for a 4-byte word on the stack sw reg16, 0($sp) Stores reg16 into stack memory Now the called procedure can use reg16 -4 Stack Pointer: $sp Stack “Top” Carnegie Mellon Stack “Bottom” Increasing Addresses Stack Grows Down CS555A – Real-Time Embedded Systems Stevens Institute of Technology CS555A – Real-Time Embedded Systems Stevens Institute of Technology Fall 2014, arz 9
#Cpe 555 stevens software
What Could Go Wrong? CS555A – Real-Time Embedded Systems Stevens Institute of Technology CS555A – Real-Time Embedded Systems Stevens Institute of Technology Fall 2014, arz 7Ĭall Stack The natural data structure for spilling registers into memory is a call stack (a last-in first-out structure) Register values are pushed and saved on the stack when the procedure is called and popped from the stack into the original register at return Historically call stacks “grow” from High address to low address A stack pointer is used to address the first unused memory location MIPS software uses register 29 for stack pointer and refers to it as $sp other machines (e.g., 80x86) may use a special-purpose stack pointer High Address main Proc1 Proc2 Proc3 $sp Proc4 Low Address CS555A – Real-Time Embedded Systems Stevens Institute of Technology CS555A – Real-Time Embedded Systems Stevens Institute of Technology Fall 2014, arz 8 Procedure Call: Return 6 26 opcode=3 immediate J-Type Format CS555A – Real-Time Embedded Systems Stevens Institute of Technology CS555A – Real-Time Embedded Systems Stevens Institute of Technology Fall 2014, arz 4Įxample CS555A – Real-Time Embedded Systems Stevens Institute of Technology CS555A – Real-Time Embedded Systems Stevens Institute of Technology Fall 2014, arz 5Īrgument Passing & Return Value CS555A – Real-Time Embedded Systems Stevens Institute of Technology CS555A – Real-Time Embedded Systems Stevens Institute of Technology Fall 2014, arz 6 CS555A – Real-Time Embedded Systems Stevens Institute of Technology CS555A – Real-Time Embedded Systems Stevens Institute of Technology Fall 2014, arz 3
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