#include "cve.h"

/* C[, j] = A[, j] * v for each j = 1 to ncol */
void rowSweep(const double *A, const int nrow, const int ncol,
              const char* op,
              const double *v, // vector of length nrow
              double *C) {
    int i, j, block_size, block_size_i;
    const double *A_block = A;
    double *C_block = C;
    const double *A_end = A + nrow * ncol;

    if (nrow > CVE_MEM_CHUNK_SMALL) { // small because 3 vectors in cache
        block_size = CVE_MEM_CHUNK_SMALL;
    } else {
        block_size = nrow;
    }

    if (*op == '+') {
        // Iterate `(block_size_i, ncol)` submatrix blocks.
        for (i = 0; i < nrow; i += block_size_i) {
            // Set `A` and `C` to block beginning.
            A = A_block;
            C = C_block;
            // Get current block's row size.
            block_size_i = nrow - i;
            if (block_size_i > block_size) {
                block_size_i = block_size;
            }
            // Perform element wise operation for block.
            for (; A < A_end; A += nrow, C += nrow) {
                for (j = 0; j < block_size_i; ++j) {
                    C[j] = A[j] + v[j]; // FUN = '+'
                }
            }
            // Step one block forth.
            A_block += block_size_i;
            C_block += block_size_i;
            v += block_size_i;
        }
    } else if (*op == '-') {
        // Iterate `(block_size_i, ncol)` submatrix blocks.
        for (i = 0; i < nrow; i += block_size_i) {
            // Set `A` and `C` to block beginning.
            A = A_block;
            C = C_block;
            // Get current block's row size.
            block_size_i = nrow - i;
            if (block_size_i > block_size) {
                block_size_i = block_size;
            }
            // Perform element wise operation for block.
            for (; A < A_end; A += nrow, C += nrow) {
                for (j = 0; j < block_size_i; ++j) {
                    C[j] = A[j] - v[j]; // FUN = '-'
                }
            }
            // Step one block forth.
            A_block += block_size_i;
            C_block += block_size_i;
            v += block_size_i;
        }
    } else if (*op == '*') {
        // Iterate `(block_size_i, ncol)` submatrix blocks.
        for (i = 0; i < nrow; i += block_size_i) {
            // Set `A` and `C` to block beginning.
            A = A_block;
            C = C_block;
            // Get current block's row size.
            block_size_i = nrow - i;
            if (block_size_i > block_size) {
                block_size_i = block_size;
            }
            // Perform element wise operation for block.
            for (; A < A_end; A += nrow, C += nrow) {
                for (j = 0; j < block_size_i; ++j) {
                    C[j] = A[j] * v[j]; // FUN = '*'
                }
            }
            // Step one block forth.
            A_block += block_size_i;
            C_block += block_size_i;
            v += block_size_i;
        }
    } else if (*op == '/') {
        // Iterate `(block_size_i, ncol)` submatrix blocks.
        for (i = 0; i < nrow; i += block_size_i) {
            // Set `A` and `C` to block beginning.
            A = A_block;
            C = C_block;
            // Get current block's row size.
            block_size_i = nrow - i;
            if (block_size_i > block_size) {
                block_size_i = block_size;
            }
            // Perform element wise operation for block.
            for (; A < A_end; A += nrow, C += nrow) {
                for (j = 0; j < block_size_i; ++j) {
                    C[j] = A[j] / v[j]; // FUN = '/'
                }
            }
            // Step one block forth.
            A_block += block_size_i;
            C_block += block_size_i;
            v += block_size_i;
        }
    }
}