What is a Compiler? What is Ada?
A compiler is a computer program that transforms "source code" written by a programmer into the "machine language" that a computer can understand.
Programmers write source code in a computer language, such as Ada, Pascal, C, C++, Cobol, Fortran, BASIC, or Java. These languages have a specific structure, syntax, and rules the programmer must follow. The compiler takes this source code and translates it into specific steps that the processor can understand. The resulting machine language can only be understood by a specific processor, such as a Pentium, PowerPC, 68000, Alpha AXP, or Intel i960 MX.
Here's an example:
Source Code (written in Ada)
while (row <= max) and (col <= max) loop if is_safe(row, col) then set_queen(row, col); col := col+1; row := min; else row := row+1; end if; end loop;
The compiler translates this into Assembly Language (for Intel i960 MX)
.I6.295: # --label_295-- ldis 40(r3),g7 cmpibg.f r4,g7,.I6.296 cmpibg.f r7,g7,.I6.296 mov r7,g1 mov r4,g0 lda 64(fp),g12 callj _QueensnIs_safe289 cmpobe.f 0,g0,.I6.298 mov r7,g1 mov r4,g0 callj _QueensnSet_queen283 addi r7,1,r7 mov g14,r4 b .I6.295 .I6.298: # --label_298-- addi r4,1,r4 b .I6.295 .I6.296: # --label_296--
The assembly language gets translated into code that the processor can run:
40002E20: C8B8E028 40002E24: 3925C03E 40002E28: 393DC03A 40002E2C: 5C881607 40002E30: 5C801604 40002E34: 8CE7E040 40002E38: 09FFFF08 40002E3C: 3204201E 40002E40: 5C881607 40002E44: 5C801604 40002E48: 09FFFE68 40002E4C: 59385087 40002E50: 5C20161E 40002E54: 08FFFFCC
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Last modified 5/13/02. Comments to email@example.com