MPLAB C32 C COMPILER USER'S GUIDE

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<strong>MPLAB</strong> ® <strong>C32</strong> C Compiler User’s GuideTABLE 1-5:Option-Wunused-parameter-Wunused-variable-Wunused-valueWARNING AND ERROR OPTIONS IMPLIED BY-WALL (CONTINUED)DefinitionWarn whenever a function parameter is unused aside from itsdeclaration. To suppress this warning, use the unusedattribute.Warn whenever a local variable or non-constant staticvariable is unused aside from its declaration. To suppress thiswarning, use the unused attribute.Warn whenever a statement computes a result that isexplicitly not used. To suppress this warning, cast theexpression to void.DS51686A-page 22© 2007 Microchip Technology Inc.
Language SpecificsThe following -W options are not implied by -Wall. Some of them warn aboutconstructions that users generally do not consider questionable, but which you mightoccasionally wish to check for. Others warn about constructions that are necessary orhard to avoid in some cases, and there is no simple way to modify the code to suppressthe warning.TABLE 1-6: WARNING AND ERROR OPTIONS NOT IMPLIED BY-WALLOptionDefinition-W Print extra warning messages for these events:• A nonvolatile automatic variable might be changed by acall to longjmp. These warnings are possible only inoptimizing compilation. The compiler sees only the callsto setjmp. It cannot know where longjmp will be called.In fact, a signal handler could call it at any point in thecode. As a result, a warning may be generated evenwhen there is in fact no problem, because longjmpcannot in fact be called at the place that would cause aproblem.• A function could exit both via return value; andreturn;. Completing the function body without passingany return statement is treated as return;.• An expression-statement or the left-hand side of acomma expression contains no side effects. To suppressthe warning, cast the unused expression to void. Forexample, an expression such as x[i,j] causes awarning, but x[(void)i,j] does not.• An unsigned value is compared against zero with < or
Page 1 and 2: MPLAB C32C COMPILERUSER’S GUIDE©
Page 3 and 4: Table of ContentsMPLAB ® C32 C COM
Page 5 and 6: PrefaceMPLAB ® C32 C COMPILERUSER
Page 7 and 8: PrefaceRECOMMENDED READINGThis user
Page 9 and 10: PrefaceDEVELOPMENT SYSTEMS CUSTOMER
Page 11 and 12: Chapter 1. Language SpecificsMPLAB
Page 13 and 14: Language Specifics1.5.6 limits.hThe
Page 15 and 16: Language Specifics__mips___mips_MIP
Page 17 and 18: Language SpecificsThe first_to_chec
Page 19 and 20: Language SpecificsGenerate a branch
Page 21 and 22: Language Specifics1.8.2 Options for
Page 25: Language SpecificsTABLE 1-5:-Wswitc
Page 29 and 30: Language SpecificsTABLE 1-6:-Wredun
Page 33 and 34: Language SpecificsTABLE 1-9: SPECIF
Page 35 and 36: Language SpecificsOptions of the fo
Page 37 and 38: Language SpecificsTABLE 1-11:-I--Id
Page 39 and 40: Language SpecificsTABLE 1-11: PREPR
Page 41 and 42: Language Specifics1.8.10 Options fo
Page 43 and 44: Language SpecificsTABLE 1-15:Option
Page 45 and 46: Language Specifics1.10 COMPILING MU
Page 47 and 48: MPLAB ® C32 C COMPILERUSER’S GUI
Page 49 and 50: Library Environment2.6.2 What Multi
Page 51 and 52: Chapter 3. InterruptsMPLAB ® C32 C
Page 53 and 54: Interrupts3.4.2 Vector PragmaThe ve
Page 57 and 58: Low Level Processor Control4.6 SPEC
Page 59 and 60: Low Level Processor Control4.8.1.1
Page 63 and 64: Compiler Runtime Environment5.5 HEA
Page 65 and 66: Compiler Runtime Environment5.7 STA
Page 67 and 68: Compiler Runtime EnvironmentWithout
Page 69 and 70: Compiler Runtime EnvironmentFIGURE
Page 71 and 72: Compiler Runtime Environment5.7.2.9
Page 73 and 74: Compiler Runtime Environment5.7.2.9
Page 75 and 76: Compiler Runtime Environment• The
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Compiler Runtime Environment5.7.4 S
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Compiler Runtime Environment5.8.3 P
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Compiler Runtime Environment(i.e.,
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Compiler Runtime Environment5.8.4.4
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Compiler Runtime Environment.dbg_da
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Compiler Runtime Environment*/. = A
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Compiler Runtime Environment5.9 RAM
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MPLAB ® C32 C COMPILERUSER’S GUI
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Implementation Defined BehaviorISO
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Implementation Defined BehaviorImpl
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MPLAB ® C32 C COMPILERUSER’S GUI
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IndexMPLAB ® C32 C COMPILERUSER’
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IndexCHAR_BIT .....................
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Indexread..........................
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Index-fcaller-saves ...............
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IndexStack Location ...............
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IndexNOTES:© 2007 Microchip Techno
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