Machine level representation of c programs where the

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Unformatted text preview: ¡½ . Finally, the code can use a simple counter to keep track of the number of iterations required. We have shown the C code fix_prod_ele_opt to illustrate the optimizations made by the C compiler in generating the assembly. The actual assembly code for the loop is shown below. Aptr is in %edx, Bptr in %ecx, result in %esi, cnt in %ebx loop: Compute t = *Aptr 1 2 .L23: movl (%edx),%eax 3.8. ARRAY ALLOCATION AND ACCESS 149 code/asm/array.c 1 2 3 4 5 6 7 8 9 10 11 12 13 14 #define N 16 typedef int fix_matrix[N][N]; /* Compute i,k of fixed matrix product */ int fix_prod_ele (fix_matrix A, fix_matrix B, { int j; int result = 0; for (j = 0; j < N; j++) result += A[i][j] * B[j][k]; return result; } code/asm/array.c int i, int k) (a) Original C code code/asm/array.c 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 /* Compute i,k of fixed matrix product */ int fix_prod_ele_opt(fix_matrix A, fix_matrix B, int i, int k) { int *Aptr = &A[i][0]; int *Bptr = &B[0][k]; int cnt = N - 1; int result = 0; do { result += (*Aptr) * (*Bptr); Aptr += 1; Bptr += N; cnt--; } while (cnt >= 0); return result; } c...
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This note was uploaded on 09/02/2010 for the course ELECTRICAL 360 taught by Professor Schultz during the Spring '10 term at BYU.

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