Appendix: Function Definitions

This appendix contains the function definitions (arguments, return values, error codes) for all the provided utility functions and all the functions you need to implement.

Utilities: Memory Allocation

malloc

malloc: Allocates heap memory.
Arguments a0 int The size of the memory that we want to allocate (in bytes).
Return values a0 void * A pointer to the allocated memory. If the allocation failed, this value is 0.

free

free: Frees heap memory.
Arguments a0 void * A pointer to the allocated memory to be freed.
Return values None

Utilities: File Operations

fopen

fopen: Open a file for reading or writing.
Arguments a0 char * A pointer to the filename string.
a1 int Permission bits. 0 for read-only, 1 for write-only.
Return values a0 int A file descriptor. This integer can be used in other file operation functions to refer to the opened file. If opening the file failed, this value is -1.

fread

fread: Read bytes from a file to a buffer in memory. Subsequent reads will read from later parts of the file.
Arguments a0 int The file descriptor of the file we want to read from, previously returned by fopen.
a1 int* A pointer to the buffer where the read bytes will be stored.
a2 int The number of bytes to read from the file.
Return values a0 int The number of bytes actually read from the file. If this differs from the argument provided in a2, then we either hit the end of the file or there was an error.

fwrite

fwrite: Write bytes from a buffer in memory to a file. Subsequent writes append to the end of the existing file.
Arguments a0 int The file descriptor of the file we want to write to, previously returned by fopen.
a1 void * A pointer to a buffer containing what we want to write to the file.
a2 int The number of elements to write to the file.
a3 int The size of each element. In total, a2 × a3 bytes are written.
Return values a0 int The number of items actually written to the file. If this differs from the number of items specified (a2), then we either hit the end of the file or there was an error.

fclose

fclose: Close a file, saving any writes we have made to the file.
Arguments a0 int The file descriptor of the file we want to close, previously returned by fopen.
Return values a0 int 0 on success, and -1 otherwise.

Utilities: Printing

print_int: Prints an integer.
Arguments a0 int The integer to print.
Return values None
print_char: Prints a character.
Arguments a0 char The character to print. You can provide the ASCII code or put the character directly in the register like li t0 '\n'.
Return values None

Part A

relu

relu: Task 2.
Arguments a0 int * A pointer to the start of the integer array.
a1 int The number of integers in the array. You can assume that this argument matches the actual length of the integer array.
Return values None

argmax

argmax: Task 3.
Arguments a0 int * A pointer to the start of the integer array.
a1 int The number of integers in the array. You can assume that this argument matches the actual length of the integer array.
Return values a0 int The index of the largest element. If the largest element appears multiple times, return the smallest index.

dot

dot: Task 4.
Arguments a0 int * A pointer to the start of the first array.
a1 int * A pointer to the start of the second array.
a2 int The number of elements to use in the calculation.
a3 int The stride of the first array.
a4 int The stride of the second array.
Return values a0 int The dot product of the two arrays, using the given number of elements and the given strides.

Testing functions

Loss functions: Task 5.
Arguments a0 int * A pointer to the start of the first input array.
a1 int * A pointer to the start of the second input array.
a2 int The number of integers in the array.
a3 int * A pointer to the start of the output array, where the results will be stored.
Return values a0 int The sum of the elements in the output array. (No return value for zero-one loss.)
initialize_zero: Task 5.
Arguments a0 int The size of the array to be created.
Return values a0 int * A pointer to the newly-allocated array of zeros.

Part B

matmul

matmul: Task 6.
Arguments a0 int * A pointer to the start of the first matrix A (stored as an integer array in row-major order).
a1 int The number of rows (height) of the first matrix A.
a2 int The number of columns (width) of the first matrix A.
a3 int * A pointer to the start of the second matrix B (stored as an integer array in row-major order).
a4 int The number of rows (height) of the second matrix B.
a5 int The number of columns (width) of the second matrix B.
a6 int * A pointer to the start of an integer array where the result C should be stored. You can assume this memory has been allocated (but is uninitialized) and has enough space to store C.
Return values None

read_matrix

read_matrix: Task 7.
Arguments a0 char * A pointer to the filename string.
a1 int * A pointer to an integer which will contain the number of rows. You can assume this points to allocated memory.
a2 int * A pointer to an integer which will contain the number of columns. You can assume this points to allocated memory.
Return values a0 int * A pointer to the matrix in memory.

write_matrix

write_matrix: Task 8.
Arguments a0 char * A pointer to the filename string.
a1 int * A pointer to the matrix in memory (stored as an integer array).
a2 int The number of rows in the matrix.
a3 int The number of columns in the matrix.
Return values None

classify

classify: Task 9.
Arguments a0 int argc (the number of arguments provided)
a1 char ** argv, a pointer to an array of argument strings (char *)
a1[1] = *(a1 + 4) char * A pointer to the filepath string of the first matrix file m0.
a1[2] = *(a1 + 8) char * A pointer to the filepath string of the second matrix file m1.
a1[3] = *(a1 + 12) char * A pointer to the filepath string of the input matrix file input.
a1[4] = *(a1 + 16) char * A pointer to the filepath string of the output file.
a2 int If set to 0, print out the classification. Otherwise, do not print anything.
Return values a0 int The classification (see above).

Error Codes

Part A

Return code Exception Functions
26 malloc returns an error. initialize_zero (5)
36 The length of the array is less than 1. relu (2), argmax (3), dot (4), loss functions (5), initialize_zero (5)
37 The stride of either array is less than 1. dot (4)

Part B

Return code Exception Functions
26 malloc returns an error. read_matrix (7), classify (9)
27 fopen returns an error. read_matrix (7), write_matrix (8)
28 fclose returns an error. read_matrix (7), write_matrix (8)
29 fread does not read the correct number of bytes. read_matrix (7)
30 fwrite does not write the correct number of bytes. write_matrix (8)
31 There are an incorrect number of command line arguments. classify (9)
38 The height or width of either matrix is less than 1. matmul (6)
38 The number of columns (width) of the first matrix A is not equal to the number of rows (height) of the second matrix B. matmul (6)