(I know and prefer Intel/MASM syntax, so I will use that. Note that the order of operands is reversed in AT&T.)
Your instruction is actually a two-operand imul, which in Intel syntax is:
imul eax, DWORD PTR [ebp + ebx*4 + 0FFFFFFD4h]
Where eax is the destination operand and the memory location is the source operand. The two-operand imul performs a multiplication of the source and destination operands and stores the result in the destination. Unlike 1-operand, it doesn t write a high half anywhere, so the same instruction works for signed and unsigned, like with add and left shift.
This instruction is multiplying a register by the integer in an array. Most likely this appears in a loop and the array is a local variable (on the stack starting at ebp-44).
The three-operand imul instruction is:
imul dest, source1, immediate
imul reg, r/m, imm ; showing what kind of operand is allowed
The source1 operand (either a memory location or a register) is multiplied by the immediate operand (either an 8-bit or 16/32-bit constant) and the result is stored in the dest operand (a 16, 32 or 64-bit register).
See Intel s manual entry for imul: https://www.felixcloutier.com/x86/imul
