The document discusses ARM7 multiplication instructions. It describes six instructions: MUL, MLA, UMULL, UMLAL, SMULL, and SMLAL. MUL multiplies two 32-bit registers and stores the lower 32 bits of the result. The other instructions multiply 32-bit registers to produce 64-bit results. UMULL, UMLAL, SMULL, and SMLAL retain all 64 bits of the product, while MLA also allows accumulating a multiplication with the contents of another register. Examples are given of using each instruction type.

1. ARM7 Programming
Data Processing Instructions MUL Instructions
ARM7 Programming - Instructions1
By
Mr.Vishal S. Gaikwad

2. Multiplication Instructions
ARM7 Programming - Instructions2
 ARM provides two multiplication instructions
 MUL - Multiply
 MLA - Multiply Accumulate
 UMULL - Unsigned Long Multiply
 UMLAL - Unsigned Long Multiply, with Accumulate
 SMULL - Signed Long Multiply
 SMLAL - Signed Long Multiply, with Accumulate

3. Multiplication Instructions
ARM7 Programming - Instructions3
 MUL - Multiply
 MUL (Multiply) is the simplest multiplication instruction.
 It multiplies two 32-bit numbers (held in registers) and stores a 32-bit result in a destination register.
 Multiplying two 32-bit numbers together gives rise to a 64-bit number.
 The MUL instruction only stores the lower 32 bits of the product.
 The ARM also has four instructions for multiplying 32-bit numbers together
and retaining all 64 bits of the product, these are,
UMULL, UMLAL, SMULL, SMLAL

4. MUL, MLA - Instruction Format
ARM7 Programming - Instructions4
Multiply and multiply-accumulate (32-bit by 32-bit, bottom 32-bit result).

5. MUL, MLA - Instruction Use
ARM7 Programming - Instructions5

6. MUL, MLA - Example
ARM7 Programming - Instructions6
 MUL R0, R1, R2 ; R0 = R1 * R2
 MLA r10,r2,r1,r5 ; r10= (r1*r2) + r5
 MULS r0,r2,r2

7. UMULL, UMLAL,SMULL,SMLAL - Instruction Format
ARM7 Programming - Instructions7
Unsigned and signed long multiply and multiply accumulate (32-bit by 32-bit, 64-bit accumulate or result).

8. UMULL, UMLAL,SMULL,SMLAL - Instruction Use
ARM7 Programming - Instructions8

9. UMULL, UMLAL,SMULL,SMLAL - Example
ARM7 Programming - Instructions9
 UMULL r0, r4, r5, r6 ; (r4:r0) = r5 * r6
 UMLAL r4, r5, r3, r8 ; (r4:r5) =(r3*r8) + (r5:r4)
 The UMLAL instruction performs a multiplication on unsigned operands Rm and Rs . The 64-bit
result of the multiplication is added to RdLo and RdHi. The sum is written to RdLo and RdHi.
 SMLAL R4, R5, R3, R8 ; (R5:R4) = (R5:R4) + (R3*R8)
 SMULL r0, r4, r5, r6 ; (r4:r0) = r5 * r6

10. ARM7 Programming - Instructions10
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