SPRUIG5E January   2018  – March 2023 TDA4VM , TDA4VM-Q1

 

  1.   Abstract
  2. 1About This Document
    1. 1.1 Related Documents
    2. 1.2 Trademarks
  3. 2Migrating C Source from C6000 to C7000
    1. 2.1  Compiler Options
    2. 2.2  Native Vector Data Types
    3. 2.3  Type Qualifiers: near and far
    4. 2.4  64-bit long Type
    5. 2.5  References to Control Registers
    6. 2.6  Memory-Mapped Peripherals
    7. 2.7  Run-Time Support
    8. 2.8  Contents of Migration Header File c6x_migration.h
      1. 2.8.1 Supported Macros
      2. 2.8.2 Non-Supported Macros
      3. 2.8.3 Legacy Data Types
      4. 2.8.4 Legacy Intrinsics
    9. 2.9  Galois Field Multiply Instructions
    10. 2.10 Performance Considerations for Migrated Code
      1. 2.10.1 UNROLL Pragma
      2. 2.10.2 Subvector Access
      3. 2.10.3 16x16 and 16x32 Bit Multiplies
      4. 2.10.4 __x128_t Type
      5. 2.10.5 Unsigned Array Offsets
      6. 2.10.6 Streaming Engine and Streaming Address Generator
      7. 2.10.7 Additional Optimization Guidance
  4. 3Host Emulation
  5. 4Revision History
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    2.     30

2.10.5 Unsigned Array Offsets

C7000 does not support using a 32-bit unsigned value in a register for an offset to a load or store. The compiler may need to do this if an unsigned integer is used for an array offset. This may also occur if an enum type is used for an array offset and all members of the enum type are positive. Such loads/stores will be emulated using individual offset scaling, addition, and load/store instructions. This emulation may affect performance.

You can avoid this behavior by using the 32-bit signed integer type for array offsets.