/****************************************************/
/* File: code.c */
/* TM Code emitting utilities */
/* implementation for the TINY compiler */
/* Compiler Construction: Principles and Practice */
/* Kenneth C. Louden */
/****************************************************/
#include "globals.h"
#include "code.h"
/* TM location number for current instruction emission */
static int emitLoc = 0 ;
/* Highest TM location emitted so far
For use in conjunction with emitSkip,
emitBackup, and emitRestore */
static int highEmitLoc = 0;
/* Procedure emitComment prints a comment line
* with comment c in the code file
*/
void emitComment( char * c )
{ if (TraceCode) fprintf(code,"* %s\n",c);}
/* Procedure emitRO emits a register-only
* TM instruction
* op = the opcode
* r = target register
* s = 1st source register
* t = 2nd source register
* c = a comment to be printed if TraceCode is TRUE
*/
void emitRO( char *op, int r, int s, int t, char *c)
{ fprintf(code,"%3d: %5s %d,%d,%d ",emitLoc++,op,r,s,t);
if (TraceCode) fprintf(code,"\t%s",c) ;
fprintf(code,"\n") ;
if (highEmitLoc < emitLoc) highEmitLoc = emitLoc ;
} /* emitRO */
/* Procedure emitRM emits a register-to-memory
* TM instruction
* op = the opcode
* r = target register
* d = the offset
* s = the base register
* c = a comment to be printed if TraceCode is TRUE
*/
void emitRM( char * op, int r, int d, int s, char *c)
{ fprintf(code,"%3d: %5s %d,%d(%d) ",emitLoc++,op,r,d,s);
if (TraceCode) fprintf(code,"\t%s",c) ;
fprintf(code,"\n") ;
if (highEmitLoc < emitLoc) highEmitLoc = emitLoc ;
} /* emitRM */
/* Function emitSkip skips "howMany" code
* locations for later backpatch. It also
* returns the current code position
*/
int emitSkip( int howMany)
{ int i = emitLoc;
emitLoc += howMany ;
if (highEmitLoc < emitLoc) highEmitLoc = emitLoc ;
return i;
} /* emitSkip */
/* Procedure emitBackup backs up to
* loc = a previously skipped location
*/
void emitBackup( int loc)
{ if (loc > highEmitLoc) emitComment("BUG in emitBackup");
emitLoc = loc ;
} /* emitBackup */
/* Procedure emitRestore restores the current
* code position to the highest previously
* unemitted position
*/
void emitRestore(void)
{ emitLoc = highEmitLoc;}
/* Procedure emitRM_Abs converts an absolute reference
* to a pc-relative reference when emitting a
* register-to-memory TM instruction
* op = the opcode
* r = target register
* a = the absolute location in memory
* c = a comment to be printed if TraceCode is TRUE
*/
void emitRM_Abs( char *op, int r, int a, char * c)
{ fprintf(code,"%3d: %5s %d,%d(%d) ",
emitLoc,op,r,a-(emitLoc+1),pc);
++emitLoc ;
if (TraceCode) fprintf(code,"\t%s",c) ;
fprintf(code,"\n") ;
if (highEmitLoc < emitLoc) highEmitLoc = emitLoc ;
} /* emitRM_Abs */
