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VHDL / Sequential Statements

while loop

Learn while loop in VHDL through a focused explanation, a dedicated construct-specific example, an engineering boundary, and a mastery check.

10 min read • Intermediate

while loop is an atomic VHDL topic inside Sequential Statements. This lesson focuses on how the while loop construct is written, what it changes, and when it is the right tool.

Trace the example line by line. Identify the exact syntax for while loop, the input state before it runs, and the resulting value, control flow, database state, hardware behavior, or runtime effect afterward. Neighboring lessons use different constructs rather than renamed copies of this one.

Topic-specific example

vhdl-05-04-while-loop.vhd
vhdl Try It Live 
process variable i:integer:=0; begin while i<4 loop i:=i+1; end loop; report integer'image(i); wait; end process;
Edge case / engineering note

For while loop, test the boundary that belongs to this exact feature rather than a generic failure case. Check invalid or empty input, NULL/unknown state, numeric limits, transaction or exception behavior, synthesis/runtime constraints, ownership/permission rules, or backtracking/control-flow effects where they apply.

Content source & attribution
Original Syntaxis Content · Original Syntaxis Content

Lesson quizzes

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