Target agnostic interface for 8-bit matrix multiply for wasm

src/tensors/cpu/wasm_intgemm_interface.h

@@ -0,0 +1,54 @@
+#pragma once
+
+/* Main interface for integer matrix multiplication (C = A * B) for wasm.
+ *
+ * A is typically activations whose rows should be a multiple of 1 (i.e. no restriction) and
+ * columns should be a multiple of 64.
+ * 
+ * B is typically fixed model parameters whose rows should be a multiple of 64 and columns
+ * should be a multiple of 8.
+ * 
+ * C is row major.
+ */
+
+#include <cstdint>
+
+using Index = unsigned int;
+
+// A structure holding 8-bit quantized values and the associated quantization parameters.
+typedef struct QuantizedBuffer {
+    int8_t* value;
+    float scale;
+    int8_t zero_point;
+} QuantizedBuffer;
+
+
+/* Prepare B in a CPU-dependent format from an already quantized, transposed (routine not provided)
+ * and CPU-independent format of B. The prepared B will be used as an input to Multiply routine.
+ * This function is useful while using the quantized models that are stored in a CPU-independent
+ * format on the disk.
+ */
+void Int8PrepareBQuantizedTransposed(const QuantizedBuffer& B_input, QuantizedBuffer& output, Index inner, Index B_untransposed_cols);
+
+
+/* Select columns from a prepared B matrix. The number of selected columns must be a multiple of 8.
+ */
+void Int8SelectColumnsB(const QuantizedBuffer& B_input, QuantizedBuffer& output, Index rows, const Index* cols_begin, const Index* cols_end);
+
+
+/* Prepare A for the Multiply routine that performs unsigned * signed multiplication. It performs quantization
+ * on floating values and adds 127 to each number to make sure that all numbers are positive.
+ */
+void Int8ShiftPrepareA(const float* A_input, QuantizedBuffer& output, Index rows, Index cols);
+
+
+/* Prepares bias for the Multiply routine that performs unsigned * signed multiplication.
+ */
+void Int8ShiftPrepareBias(const QuantizedBuffer& B_input, const float* bias_input, QuantizedBuffer& output, Index width, Index B_cols);
+
+
+/* A multiply routine to perform unsigned * signed multiplication.
+ * It does C = A * B + Bias, presuming A, B and Bias are quantized inputs prepared using the
+ * corresponding Prepare* functions.
+ */
+void Int8ShiftMultiply(const QuantizedBuffer& A_input, const QuantizedBuffer& B_input, const QuantizedBuffer& bias_input, float* output, Index A_rows, Index width, Index B_cols);